would help win many more battles in the future. As the Germans swept through Holland, Belgium and into France, they sent more than a thousand Enigma messages a day and at times
the entire hut was overwhelmed, with many of the staff, including the young women in the Registration and Decoding Rooms, working nonstop and not going home. Diana remembered snatching a few
precious moments’ sleep on the floor of the Decoding Room.
‘There was a time when we were working certainly forty-eight hours on end because there was a lot of traffic coming through and they hadn’t really got enough staff and the stuff
perhaps would stop for a bit and we just used to put our coats under our head and lie on the floor and go to sleep.’
But the large number of messages being sent by the Germans helped the bright young codebreakers in the Machine Room break back into the Red, in large part due to some extremely clever thinking
by John Herivel, one of the Cambridge mathematicians. He put himself intothe mind of a German Enigma operator and worked out a mistake that tired operators might make. Ten
days into the battle, several operators all made that very same mistake and Hut 6 was back into the Red Enigma, guaranteeing that they would produce good intelligence for the rest of the war.
Everyone in the Machine Room was cheering and shouting and the elation was felt throughout the hut.
MI6 sent communication experts and intelligence officers out to France to pass on the codebreakers’ reports to the British commanders but the Allied forces were overwhelmed and it had
little effect. The British troops had to be evacuated from Dunkirk by several dozen Royal Navy ships and a volunteer armada of small boats from England’s southern ports which helped to lift
the soldiers off the beaches. Just as the codebreakers had listened in the mansion to Mr Chamberlain telling them on the BBC they were at war with Germany, so in June 1940 they listened to Mr
Churchill saying that they would ‘ride out the storm of war, and outlive the menace of tyranny, if necessary for years, if necessary alone’.
It was stirring stuff. Britain would never surrender, the Prime Minister said. ‘We shall defend our Island, whatever the cost may be. We shall fight on the beaches and on the landing
grounds. We shall fight in the fields and in the streets. We shall fight in the hills.’ The staff at Bletchley listened and, despite their worries, they were proud. They knew Britain was now
alone, but they also knew that they had the opportunity, a unique opportunity, to help to win the war.
Britain collectively waited for what seemed the inevitable German invasion. Bletchley Park set up its own ratherodd-ball ‘Dad’s Army’ Home Guard
detachment, with Alan Turing as one of the unlikely defenders, and plans were made to set up a mobile codebreaking team that would be evacuated if the Germans invaded to keep breaking the codes and
provide the vital intelligence. Phoebe Senyard was bemused by the reaction of some of the codebreakers.
‘The war situation was now becoming very grim for us. The air was electric with feeling. Those who had been chosen were in a sense excited by the prospect before them, although no doubt
dismayed by the reason for their evacuation. I was surprised by the number of people whose feelings were hurt because they had not been included on the list.’
In another rousing speech, Mr Churchill told the nation that while the Battle for France had been lost, the Battle of Britain was about to begin. They should brace themselves to do their duty so
that if Britain, its Empire and its Commonwealth were to last for a thousand years, men would still say: ‘This was their finest hour.’
The Germans attempted to intimidate Britain ahead of Hitler’s planned invasion, Operation Sea Lion, testing the ability of the RAF to defend the skies above southern England. RAF
Hurricanes and Spitfires circled the skies, taking on the German