*Introduction to the theory of finite groups*was based on Schur's lectures on group theory. The book was written at the time that Ledermann was an assistant lecturer at St Andrews. The teaching term kept him fully occupied so the writing of the book took place during the summer vacation. Ledermann's parents lived in London at that time and he spent the summer in London visiting them. He obtained a ticket to use the British Museum Library and the book was written there. A seat was reserved for him every day, as were the texts which he was using from the library. In fact the seat on which he wrote the book was the same one that Karl Marx had used 80 years earlier when he wrote Das Kapital in the British Museum Library.

*Introduction to the theory of finite groups* first appeared in 1949. The original book went through many editions before it was retitled *Introduction to group theory*. Because of paper shortages caused by World War II the first two editions did not have dust covers, the third edition being the first with this added feature. The fourth edition of *Introduction to group theory* appeared in 1994.

At an after lunch speech at a conference at the University of Sussex on 19 March 2001 to celebrate his 90th birthday, Walter Ledermann spoke about the book. He remarked that having been written on at the same seat as Karl Marx used seemed to rub off on the book on one occasion. Ledermann lectured on group theory at the University of Notre Dame in the United States. In order that the students would be able to buy the *Introduction to the theory of finite groups* copies were ordered through the publisher Oliver & Boyd in Edinburgh. A parcel containing the books was sent but when it was inspected on entry to the United States the officers were suspicious. "Groups of what" they asked themselves? Looking at the strange symbols inside they decided that it must refer to "groups of communists" and so the parcel of books was confiscated. Only after the chairman of the Mathematics Department at Notre Dame intervened personally and explained that there was nothing about communists in the work was it allowed to continue its journey to the Chicago bookshop.