My thanks are due to the staff of all the institutions I visited during the course of this work. Liliane Gautret was ever ready to help on technical matters, and Paul Tizard was a constant support.
Fernand Perrin and I had planned to produce this book together, but sadly, he died before the first sentence was written. He entrusted to me all of the documents he had collected, and they were invaluable, as is his memory. Ivor Grattan-Guinness was, as always, an adviser and critic second to none.