With a great many thanks, first of all, to Kelsey Griffin, Director of the Museum at Bletchley Park, for introducing me to such brilliant people. Among all those, and other, brilliant people, thanks are also due to the Honourable Sarah Baring, to Mavis and Keith Batey, Ruth Bourne, Mimi Gallilee, Simon Greenish, John Herivel, Oliver and Sheila Lawn, Trudie Marshall, Geoffrey Pidgeon, Veronica Plowman, Nicolas Ridley, Captain Jerry Roberts, Sarah and John Standing and especially to Jean Valentine. Thanks also to the Bletchley Park Trust – which has made the museum such an invaluable and fascinating draw for generations to come.