Bletchley is best known as the World War II headquarters of Britain’s famous codebreakers – Bletchley Park. Sir Herbert Leon, a wealthy stockbroker, had bought the estate in 1882 and was key in its development. In 1937, the estate passed into government hands. Then, an undercover MI6 group arrived using the name ‘Captain Ridley’s Shooting Party’, with ‘an air of friends enjoying a weekend at a country house’. Their real purpose was to see whether Bletchley Park would work as a wartime location.