ABSTRACT
Britain's peril in 1940, owing to the collapse of the Allied armies in France before the German advance, together with the Luftwaffe attacks on her cities, is well-documented, indeed imprinted on our minds and not likely to be forgotten. By 1941, an Operations Intelligence Centre had been set up in Liverpool for continuous plots of convoy routes, together with partly known, partly guessed U-boat dispositions in the Atlantic. The naval version of Enigma, more secure than the army version, had at first three rotors, set to a key changed daily, which scrambled a typed letter of the alphabet in such a manner that Calvocoressi at Intelligence Headquarters, Bletchley Park, put the figure of possible permutations as 'not far short of six thousand million'. For courage and initiative, Baker-Cresswell was awarded the Distinguished Service Order, Balme the Distinguished Service Cross.
