Penney, William George, Baron Penney

(1909-1991), mathematical physicist and public servant

by Brian Cathcart

© Oxford University Press 2004 All rights reserved

Penney, William George, Baron Penney (1909-1991), mathematical physicist and public servant, was born at 4E Block, Naval Hospital Road, Gibraltar, on 24 June 1909, the only son and eldest of the three children of William Alfred Penney (b. 1881), sergeant-major in the Royal Army Ordnance Corps, and his wife, Blanche Evelyn, daughter of Henry Alfred Johnson. Penney's mother had been chief cashier in a Co-operative store before her marriage.

Education, early career, and marriage
Penney's father served in a succession of postings in England and overseas, so his son attended a variety of schools in his early years. Young Penney was bright--he may have inherited his gift for numbers from his mother--but he often played truant because, he would say later, he found classes insufficiently demanding. Despite this, in due course he proved a good enough student to qualify for grammar school. It was not to be. His father, an authoritarian at home as at work, had little sympathy with his son's scholarly interests, besides which he knew he could not afford to maintain the boy as a boarder. So young Penney went to technical school, first in Colchester and then in his father's home town, Sheerness, Kent, where he lodged with an aunt. By good fortune, however, at Sheerness Junior Technical School he came under the influence of the principal, Albert Bell, a gifted teacher with a first-class degree in physics. Bell saw the boy's abilities, directed his interests, and helped him become a star student. Penney also flourished as a sportsman, distinguishing himself at boxing, athletics, cricket, and above all on the football field, where he played centre forward in a school team that included several future professional players.

Under Bell's guidance Penney won a Kent county scholarship and a royal scholarship to the Royal College of Science, part of Imperial College, London. This was the beginning of a whirlwind academic career. After just two years (he was granted exemption from the first year of the course) he graduated with a brilliant first in mathematics, in 1929, and after two more years, including a spell in the Netherlands at the University of Groningen, he was awarded his PhD. Thereafter he departed on a Commonwealth Fund fellowship to the University of Wisconsin, where he worked with, among others, the future Nobel prizewinner John Van Vleck, publishing a stream of papers and securing an MA. While in the United States he also toured the American west in a model A Ford he had bought, taking in such scientific landmarks as Carl Anderson's laboratory at the California Institute of Technology, Ernest Lawrence's new cyclotron at Berkeley, and the Oppenheimer brothers' ranch in the New Mexico mountains. It was not purely a scientific journey: he saw Babe Ruth play baseball and, the year being 1932, was able to watch track events at the Los Angeles Olympic games.

Penney returned to Britain in 1933 to take up an 1851 Exhibition senior studentship at Trinity College, Cambridge. Among his referees for this position was Van Vleck, who wrote:

I regard him as an exceedingly promising research man. He has an unusual gift for absorbing new developments in theoretical physics very rapidly. Also he is a hard and persistent worker. This is evidenced by the fact that he has written several papers during the time that he has been at Wisconsin. His personality is good. In view of his diligence and especially his native ability in mathematical physics, it is my belief that he could very properly be awarded an 1851 studentship. (1851 Commission records, 2 Feb 1933)
Owen Richardson, another Nobel prizewinner, took a similar view, praising Penney as 'a mathematical physicist of great power and versatility' who had achieved 'a remarkable output for his years' (1851 Commission records, 7 April 1933).

By his mid-twenties, then, William Penney (known generally as Bill) had established an international reputation in a field that was one of the most exciting in science at the time. A mathematical physicist, he was engaged in applying and interpreting the new quantum mechanics with a view to improving the understanding of the structure and behaviour of particular metals and crystals. Of all his papers, mostly written with collaborators, it was the first, 'Quantum mechanics of electrons in crystal lattices' published in the Proceedings of the Royal Society of London in 1931 with the Dutchman R. de L. Kronig, that acquired the most lasting renown. Variants of the mathematical model it set out are still in use. Other papers in the early 1930s were pathfinding, such as those relating to the photoelectric effect in thin metallic films and to the polarization of light emitted from atoms excited by electron collision. At Wisconsin and Cambridge his interest turned further towards chemistry and he published a series of papers contributing to the development of the theory of bonds. While still at Cambridge he was invited to give a course of lectures on quantum mechanics to chemists at Imperial and this grew into a monograph, The Quantum Theory of Valency (1935), which proved to be his only book. (In chemistry valency relates to the power of atoms to combine.) He was awarded a PhD by the University of Cambridge in 1935 and a DSc by the University of London in 1936.

In 1936 Penney became for a short time Stokes student at Pembroke College, Cambridge, but later the same year he returned to Imperial College full time as assistant professor of mathematics, a post he held until 1945. He was twenty-seven years old and on 27 July the previous year had married Adele Minnie Elms (1913-1945), daughter of Percy Orrin Elms, of Queensborough, Kent. Penney and his wife had known each other since Sheerness days. They had two sons, Martin (b. 1938) and Christopher (b. 1941).

Many of the characteristics that were to determine Penney's future career were by this time already evident. He was a first-class mathematician, happiest when he had a problem and a pencil and paper to solve it, but he was also a natural interpreter and teacher with a gift for explaining his very complex subject to undergraduates and lay people. In this he was helped by a remarkably easy manner. Though his background was humble he had no chip on his shoulder; on the contrary, he enjoyed throughout his life a rare ability to deal as an equal with anybody he encountered, from prime ministers to private soldiers. Nor did he have what is known as 'side'. If he had a fault in his professional relationships it was a low boredom threshold; confronted with a problem that challenged nothing but his patience, he would allow his mind to wander. Subordinates found, later in his career, that the best way to engage his attention at such moments was to find some mathematical complication to the matter in hand.

War and the atom bomb
On the outbreak of the Second World War, Penney registered as available for scientific war work, but heard nothing for several months. Then one day, he recalled later,

I met Sir Geoffrey Taylor, a world authority on fluid mechanics, and he told me he was being asked by government departments lots of questions about explosions and that sort of thing. He could not deal with all the questions and therefore asked me to have a go at the pressure wave caused by an explosion under water. (Cathcart, 30)
It was a fateful meeting, for by joining Taylor's physics of explosives committee, known as Physex, Penney entered on a career of public service that was to dominate his life for twenty-seven years. For Physex he studied and interpreted the results of both laboratory experiments and real explosions, including bomb attacks in the field, and before long he was an authority on blast waves. This led to other war work. When in 1943 the D-day planners began to contemplate the possibility of improvising a harbour on the French coast--this became the Mulberry harbour--they turned to Penney for an analysis of the physics of sea waves. The result was the Bombardon breakwaters, long steel cylinders that floated on the surface and were weighted in such a way as to absorb wave energy. These proved successful, but by then Penney was on his way to join the Manhattan Project.

In great secrecy work was under way in 1944 at a number of places in the United States to develop the nuclear fission bomb, with Britain involved as junior partner. Sir Geoffrey Taylor, acting as a consultant, had visited the laboratory at Los Alamos where the weapon was being designed and had seen a role for Penney. Once again this was to do with waves: the bomb would generate blast waves on an unprecedented scale and Penney had experience and knowledge in this field that no one in the United States could match. Though Imperial College, where he was still teaching, was reluctant to release him, Taylor was adamant and in June 1944 Penney travelled out to New Mexico.

At the Los Alamos laboratory, under the direction of J. Robert Oppenheimer, many of the world's leading physicists had been assembled to tackle the fundamental problems entailed in the design of a fission weapon. Among them were Enrico Fermi, Hans Bethe, Edward Teller, John von Neumann, and Emilio Segre, while the small British team included Otto Frisch, Rudolf Peierls, Klaus Fuchs, and for a short time Sir James Chadwick. One of Penney's first tasks there was to lecture on the science of bomb damage. Peierls described the occasion:

His presentation was in a scientific, matter-of-fact style, with his usual brightly smiling face; many of the Americans had not been exposed to such a detailed and realistic discussion of casualties, and he was nicknamed, by Viktor Weisskopf, 'the smiling killer'. (C. R. Peierls, Bird of Passage: Recollections of a Physicist, 1985, 201)
The label did not stick, and Penney's new colleagues soon came to respect and like him.

By late 1944 the team was pursuing in parallel two designs for the fission weapon. The first, with the uranium isotope 235 as its fissionable material, would employ the gun method of detonation. The weapon dropped on Hiroshima, known as Thin Man, was of this kind. The second design used plutonium and would be detonated in a different way: by implosion. A quantity of plutonium alloy would be placed at the centre of a ball of conventional high explosive, which would then be detonated. The inward blast would crush the plutonium until it reached a supercritical state, unleashing the chain reaction. Fat Man (or Fat Boy), used at Nagasaki, was a plutonium bomb. Successful implosion required a uniform convergent wave, in itself a considerable scientific challenge, and Penney, as an expert in the mathematics of waves, was inevitably drawn into this work. Looking back later on his Los Alamos period, he wrote: 'I spent about half of my time working on some of the scientific phenomena going into the bomb and the other half on scientific phenomena going outwards' (Cathcart, 35).

As the actual use of the weapons drew closer, however, it was the outward matters that came to dominate for Penney and he became an important figure. General Leslie Groves, overall director of the Manhattan Project, wrote later of the final preparations for the atomic attacks on Japan:

Throughout the life of the project, vital decisions were reached only after the most careful consideration and discussion with the men I thought were able to offer the soundest advice. Generally, for this operation, they were Oppenheimer, Von Neumann, Penney, Parsons and Ramsey. (Cathcart, 37)
For a few weeks, then, Penney found himself in the innermost councils of the project, and indeed he was a member of the committee which chose the Japanese cities to be attacked. His calculations about the effects of the weapon were greatly assisted by the Trinity test of 16 July 1945, when an implosion-type weapon was detonated in the New Mexico desert. Though he designed some of the measuring equipment that was used (notable for its simplicity) he did not witness this first atomic explosion. He had been supposed to watch from an aeroplane but unfavourable weather left him stranded at the airbase.

On the eve of the attacks on Japan he was sent to the Pacific island of Tinian, from where the atomic raids were mounted, to be on hand for last-minute adjustments. The British government, meanwhile, had named him alongside Group Captain Leonard Cheshire VC as one of its official observers for the operation. In controversial circumstances they were excluded from the first flight but on 9 August they boarded a plane shadowing the mission to Nagasaki. Penney later described watching the city disappear in dust and smoke. 'All of us were in a state of emotional shock. We realized that a new age had begun and that possibly we had all made some contribution to raising a monster that would consume us all' (Cathcart, 38). Soon he was on the ground in Hiroshima and Nagasaki, conducting field studies with a view to calculating the yield of the two weapons. His method was characteristically simple: he made a large collection of bent poles, crushed cans, and dished metal panels and took them back with him to London (where customs officials were astonished at the contents of his luggage). From these he was able to deduce the force of the explosions, although the calculations were still approximate and he would return to the problem several times in later life to refine them.

With the war over, Penney's career stood for a time in flux. His wife, Adele, had died on 18 April 1945, having suffered from postnatal depression since the birth of their second son, and he had arranged for the two boys to be cared for in Wales. Now that he was back in London they rejoined him, but Penney had decisions to make. The United States government, it seems, wanted to recruit him permanently for Los Alamos, so valuable was his expertise to them. Imperial College wanted him, as did Oxford University, which offered him a chair in mathematics. So too did the British government. It was C. P. Snow, the novelist and civil service commissioner, who suggested to Penney that he should become chief superintendent of armament research, running a large guns-and-bombs empire based at Fort Halstead in Kent and embracing stations at Woolwich and a dozen other places around the country. Normally such a post would have no interest for an academic scientist, but Snow had an ulterior motive. Britain, he said, was likely to make an atomic bomb of its own and the government wanted Penney in this job, ready to play his part. Penney recalled later: 'Snow said, "Look, you must come into the Armament Research Department, just in case. Will you do it?"' (Cathcart, 40).

This invitation was a reflection of the stature Penney had acquired both as an atomic weapons scientist and as a guide to policy makers. In both capacities he was known for combining imagination with pragmatism, for seeking simple solutions to problems, and for plain talk. Of the dozen or so senior Britons who worked at Los Alamos he stood out as the best candidate for the post Snow envisaged, just as he was the one the Americans most wanted to keep. Penney, however, had qualms. He was aware of the moral implications of the weapon and like most of his Manhattan Project colleagues was uncomfortable with them. He had seen Nagasaki bombed and had walked the devastated streets afterwards. He knew what happened to people, houses, hospitals, and schools, and on what scale, and he viewed the possibility of future nuclear war with horror. But he was also loyal and patriotic. If the British government believed that this weapon was needed for the defence of the country and the empire, and that his help was necessary to make it, then he felt he had no choice. His appointment as chief superintendent of armament research was announced on 1 January 1946. He was appointed OBE and elected FRS later the same year.

The Attlee government's stance on the atom bomb was no less ambivalent. While it supported the efforts under way to establish UN control of all aspects of atomic energy, it felt at the same time that since such efforts had only a small chance of success it must proceed in secrecy with plans for a British weapon. As a first step, therefore, in December 1945 it commissioned the building of a large pile, or reactor, at Windscale; this would be at the heart of a complex of factories producing fissionable materials for bombs. The next step, authorizing the creation of the team and the facilities to design and build a working weapon, was deferred, which meant that Penney was left in limbo.

Penney was none the less extremely busy. For one thing he had married, on 3 November 1945, the nurse who had cared for his sons; she was (Eleanor) Joan Quennell (b. 1905), daughter of George Quennell, of Brentwood, Essex. It was to be a long and happy union. For another he was recruited by the American government as a consultant to advise on the first peacetime nuclear tests, at Bikini atoll in the Pacific Ocean in July 1946. The first of these tests gave Penney an opportunity to demonstrate his particular blend of intuition and inventiveness. Many elaborate arrangements had been made to measure the yield of the bomb, but he noticed that most of them required it to explode perfectly on target. As a precaution, therefore, he had 1000 jerrycans scattered over the test site. The bomb fell off target and many of the more sophisticated devices failed to function, but Penney, by measuring the effects on his cans, was able to provide adequate readings.

Until the spring of 1947 Penney worked mostly on the analysis of the Bikini tests for the Americans. This was seen as important by the British government, not least because almost all other aspects of atomic co-operation with the USA had ended when the McMahon Act was passed by congress in 1946. Thus Penney personally kept contact alive. In June 1947, however, having finally received the official go-ahead to begin work on a British atomic bomb, he set up a secret programme within his department under the cover name Basic High Explosive Research. While he employed a few other veterans of Los Alamos as consultants (notably Klaus Fuchs), the team he built was almost entirely drawn from the staff of the department or recruited through the civil service from industry and the university graduate stream. He proved a very shrewd judge of men. The work was initially shared between Fort Halstead and Woolwich, where it took place in buildings that were fenced off for additional security, while field tests of conventional explosives were carried out at Foulness on the Essex marshes. The chosen model for the bomb was the Nagasaki design, perceived to be more powerful and to have the greater potential for development.

For the first couple of years the team's priority was to develop the electronics and ordnance necessary for successful implosion. The bomb, a sphere 5 feet in diameter, would be simultaneously detonated at thirty-two points around its surface by a powerful electrical current. This would initiate inward blast waves in the sphere, which would be altered and shaped into a single, spherical convergent wave by the use of lenses of slow explosive, so that the plutonium core would be compressed in an even, symmetrical fashion. These tasks, undertaken without American assistance, took British weapons science into new territory.

Penney's role was primarily administrative, and he found the Whitehall battles about resources and recruitment wearisome, particularly as he was hamstrung by excessive secrecy (for a time not even the whole cabinet was allowed to know of the project's existence). His burdens grew when, in 1949, it was decided that his team should also be responsible for making the inner, radioactive components of the weapon. A complete new factory capable of handling these materials was required, and the result was the atomic weapons establishment at Aldermaston. While Penney disliked the bureaucratic side of management he had no problem with his other responsibilities of strategy and leadership. His command of the science enabled him to keep a clear-sighted view of the progress of the project, while his personal gifts of motivation were formidable. Even junior scientists on his staff found him popping up at their sides, wearing his genial smile, asking shrewd, helpful questions, and offering encouragement rather than criticism. A square-built man, 5 feet 10 inches tall, he had something about him--perhaps the boyish quiff of hair, perhaps the leather elbow patches and knitted sweaters--that suggested an eternal undergraduate, with all the enthusiasm and open-mindedness which that implied. His staff were in no doubt about his scientific ability and they knew he was on their side. His popularity was enhanced by a readiness to swap jokes and talk about the latest sporting events, and he joined in the odd staff cricket game. These qualities did not dim, and became all the more vital, as time passed and timetables grew ever tighter.

The project had its set-backs. In 1950 the heart of the weapon had to be redesigned because of unforeseen problems in the arming process. Penney oversaw the changes, which substantially raised the stakes for his team: no longer a faithful copy of the Nagasaki weapon, their bomb had become an experimental design. In the same year Fuchs confessed to spying for the Soviet Union both at Los Alamos and in Britain. This was a blow to Penney, who had made considerable use of the German-born physicist, but more important was the damage the affair did to Anglo-American relations. It came at a moment when it seemed that atomic co-operation was about to resume, which would have lightened Penney's load considerably. The Fuchs affair put paid to that.

After a hectic final phase of preparation, the British bomb was tested in the Monte Bello Islands off north-west Australia on 2 October 1952. The trial, code-named operation Hurricane, was a fittingly torrid climax to five difficult years: the site was extremely remote and problematic; relations there between the scientists and the Royal Navy (which provided the necessary task force) were often poor, and the weather, which was all important, proved mercurial. Penney supervised the final phase and his good humour and confidence contributed significantly to a success that was somewhat against the odds. Within hours of the explosion he received a personal message of congratulation from Winston Churchill, the prime minister, and within days he was informed that he would be made KBE.

The Atomic Energy Authority
After operation Hurricane the UK Atomic Energy Authority (UKAEA) was created, drawing nuclear energy, weapons, and research together in a single body, and Penney became member for weapons development. He and his wife settled in an official house close to the Aldermaston site and through the rest of the 1950s he oversaw an ambitious programme of work. Besides turning the prototype into a production bomb for the RAF his department also refined the design and developed alternative models, and from 1954 onwards turned its hand to creating a British hydrogen bomb. For this last task Penney had the assistance of William Cook, who ran the programme on a day-to-day basis. Up to 1956 Penney was heavily involved in further nuclear tests in Australia, which took place against a background of growing international anxiety about fall-out. Both behind the scenes and in presenting the issues to the Australian public his gift for straight talking proved invaluable, so much so that before one series in 1956 the high commissioner in Canberra begged for him to be allowed to come out early and give press interviews:

Sir William Penney has established in Australia a reputation which is quite unique ... His appearance, his obvious sincerity and honesty, and the general impression he gives that he would rather be digging his garden--and would be, but for the essential nature of his work--have made him a public figure of some magnitude in Australian eyes. (Arnold, A Very Special Relationship, 182-3)
If the British atom bomb had been a success against the odds for Penney and his team, the H-bomb was their triumph. Tests over the Pacific in 1957 and 1958, near Malden and Christmas islands, confirmed that Britain had developed a fusion weapon with a megaton-range explosive yield. Though the United States and the Soviet Union had got there first, Britain had achieved this at remarkable speed, at a fraction of the cost, and with far fewer test explosions. Soon afterwards the United States authorities finally agreed to resume co-operation in the nuclear weapons field, prompting Macmillan, the prime minister, to acknowledge the 'tremendous achievement' of the Aldermaston scientists and engineers, whose successes were a 'major factor' in persuading the Americans to heal the breach (Arnold, A Very Special Relationship, 230). Penney played an important part in the subsequent negotiations, which laid the foundations for a unique and enduring nuclear defence partnership.

For Macmillan, Penney became a trusted adviser, briefing the cabinet on nuclear matters and also attending summit meetings with presidents Eisenhower and Kennedy. He led a British delegation to the conference in Geneva in 1958 that first explored the possibility of a nuclear test ban and in the early 1960s he threw himself into the negotiations for a comprehensive test ban treaty. He believed passionately that such a treaty would be verifiable and that it would slow dramatically, if not halt completely, the East-West nuclear arms race. When, through lack of trust, the talks ended with only the partial test ban treaty of 1963, Penney was bitterly disappointed. Though it was a substantial achievement to have ended atmospheric testing by the big powers, the option of underground tests remained open, and was taken up.

In 1957 Penney was embroiled in the aftermath of the Windscale fire, the world's first serious reactor accident, which led to a release of radioactivity into the atmosphere. Three days after it took place he was appointed to lead an inquiry into what had gone wrong. The timing was awkward for him, since an important H-bomb test in the Pacific was imminent, but he was the only senior UKAEA member available. The case was urgent, so the panel conducted an intensive investigation at Windscale and produced a report in less than a fortnight. Though it placed no blame on individuals it was no whitewash; serious procedural and organizational faults were identified, and important reforms recommended. Macmillan wrote of the report's 'scrupulous honesty and even ruthlessness' (Arnold, Windscale, 83). Despite great public anxiety, however, and contrary to the wishes of the UKAEA, the report was not published. This decision, taken by Macmillan mainly for reasons of international diplomacy, rendered the report and Penney's role in it suspect; some thought he had been involved in a cover-up. Thirty years passed before the papers were made public and the doubts erased. Though he was no specialist in reactors, Penney had applied his customary scientific rigour to the task and, given the limited time available, produced a verdict that was both clear-eyed and fair.

In 1959 Penney succeeded Sir John Cockcroft as UKAEA member for research; two years later he became deputy chairman of the authority and in 1964 he was made chairman, serving until 1967. This was a period of many difficult decisions, in which the shape and scale of Britain's nuclear energy programme were laid down. 'His was a voice of moderation', wrote Lord Sherfield, his predecessor as chairman, of their days together. 'Then, as later, he tried to avoid confrontation and controversy and to work for consensus' (Sherfield, 294-5).

Imperial College and retirement
On his retirement from the UKAEA in 1967 Penney was created a life peer as Baron Penney of East Hendred, the village near Wantage, then in Berkshire but later in Oxfordshire, where he and Lady Penney had settled in 1963. No politician, he rarely attended the House of Lords and even more rarely cast a vote. In the same year, 1967, he accepted the position of rector of Imperial College, London, a job which proved considerably more demanding than he or anyone else anticipated. The late 1960s were turbulent times for the universities and before long Penney found his gifts of leadership and diplomacy taxed to the limit in keeping the college on an even keel. 'The students were sometimes uncontrollable', he wrote later, 'the heads of departments were bewildered and angry, the rest of the staff, including the technicians, wanted a say in how everything was run' (Sherfield, 296). He introduced significant reforms to make the administration more open and flexible, while at the same time directing an expansion of the college and keeping the finances in order. Despite the many trials he remained rector for six years instead of the planned five, bowing out in September 1973. The college's Penney Laboratory was named in his honour.

Penney received many academic honours and prizes, including honorary doctorates from the universities of Melbourne, Durham, Oxford, Bath, and Reading, and the City and Guilds of London Institute; honorary fellowships of St Catherine's College, Oxford, the Manchester College of Science and Technology, Trinity College, Cambridge, and Pembroke College, Cambridge; the Rumford medal of the Royal Society; the Glazebrook medal and prize; the James Alfred Ewing medal; and the Kelvin gold medal. He was made a member of the Order of Merit in 1969, and a freeman of the City of London in 1970. In retirement he played golf, fished, grew vegetables in his garden at East Hendred, and enjoyed the company of his grandchildren. He kept an office at Aldermaston for a time, returning occasionally to work on old problems that still fascinated him, notably the yields at Hiroshima and Nagasaki.

In 1985 Penney emerged from retirement to appear before an Australian royal commission into the nuclear weapons tests in Australia. The climate of opinion at the time was extremely hostile to all things nuclear. In Australia there were suspicions that the tests had been negligently conducted and had placed civilians, notably Aboriginal people, in danger, possibly causing deaths. In Britain there was concern that servicemen involved in the tests had been needlessly exposed to radiation and that some might have contracted illnesses and died as a result. Despite his advanced years Penney testified at hearings in London and because of his past seniority he in some respects bore the brunt of these public anxieties. The questioning was aggressive and the press coverage, both in Britain and Australia, was highly unsympathetic to his case, which was that due care was taken and that the tests conformed to the internationally accepted safety standards of the time. Alarming anecdotal evidence suggesting recklessness and incompetence was given much wider currency.

In its final report the commission broadly accepted Penney's view and reserved its principal criticisms for the Australian governments of the 1950s, but this brought little comfort to a man left crushed by what he felt had been an assault on his reputation and his integrity. Lady Penney believed that the experience prompted depression and possibly a nervous breakdown, and others close to him agreed that the affair took a toll on his health, possibly shortening his life. It was in this late and unhappy period that he burnt what personal papers he had. In January 1991 he was diagnosed as suffering from cancer and a few weeks later, on 3 March, he died at his home, Orchard House, Cat Street, East Hendred, Oxfordshire. He was cremated on 8 March and his ashes were taken to his home. A memorial service was held at St Augustine's, East Hendred, on 15 March.

Although Penney was an affable, often amusing man, held in great affection by those who knew him, he did not make close friends easily. His choice of a quiet retirement reflected a self-sufficiency and a preference for privacy which were present throughout his life. After the first British nuclear test in 1952 he had been lionized as a national hero and a genius, but he told a colleague at the time that he did not want to be remembered for making an atomic bomb. He knew better than most, after all, what this weapon could do. His instinct was sound, for the popularity soon evaporated and when he eventually returned to the limelight in 1985 it was in cruelly adverse circumstances. Under pressure before the royal commission he defended not just his record but the fundamental choice of his life:

I thought we were going to have a nuclear war. The only hope I saw was that there should be a balance between East and West. That is why I did this job, not to make money. I did not make any money. What I really wanted to do was to be a professor. (Cathcart, 276)
At that time little was publicly known about his career, but more emerged in the 1990s and it showed what his close colleagues had always known. Penney was a public servant of consistent and high integrity--not perhaps a smooth man, but thoughtful, calm, and direct. Though he has been rightly described as a reluctant weaponeer, his gifts as a scientist and leader of men were indispensable to the success of the first British atomic bomb project, and he contributed enormously to subsequent weapons development (both in their time very high priorities in British government policy), while in later life at the UKAEA and at Imperial College he proved to have a wise head and a safe pair of hands.

BRIAN CATHCART

Sources  
B. Cathcart, Test of greatness: Britain's struggle for the atom bomb (1994)
Lord Sherfield, Memoirs FRS, 39 (1994), 283-302
M. Gowing and L. Arnold, Independence and deterrence: Britain and atomic energy, 1945-1952, 2 vols. (1974)
L. Arnold, A very special relationship: British atomic weapon trials in Australia (1987)
L. Arnold, Windscale 1957: anatomy of a nuclear accident (1992)
L. Arnold, Britain and the H bomb (2001)
F. M. Szasz, British scientists and the Manhattan Project (1992)
The Times (6 March 1991)
The Independent (6 March 1991)
Burke, Peerage
WWW, 1991-5
private information (2004)
CGPLA Eng. & Wales (1991)
file on W. G. Penney, ICL, Archive of the Royal Commission for the Exhibition of 1851

Archives  
ICL, college archives, corresp. and papers |  CAC Cam., corresp. with Sir Edward Bullard
CAC Cam., corresp. with Sir James Chadwick
ICL, Archive of the Royal Commission for the Exhibition of 1851, file on W. G. Penney
ICL, college archives, corresp. with Lord Jackson
Institution of Mechanical Engineers, London, corresp. with Lord Hinton
PRO, CAB 130, AB1, AB16, DEFE16, DEFE32, ADM 116, NRB  FILM  BFI NFTVA  SOUND  BBC sound archives

Likenesses  
two photographs, 1932-52, repro. in Cathcart, Test of greatness
photograph, c.1967, RS
photograph, c.1967, repro. in The Times
photograph, repro. in The Independent
photographs, Hult. Arch. [see illus.]

Wealth at death  
£183,026: probate, 7 May 1991, CGPLA Eng. & Wales


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