CHAPTER 16

The Testery: breaking

Hitler’s most secret code

jerry roberts*

I

joined the Intelligence Corps in autumn 1941. At that time few people were allowed into

the Mansion at Bletchley Park, the nerve centre. I was fortunate enough to work in the

Mansion and was one of the four founder members of the Testery, set up in October 1941

to break ‘Double Playfair’ cipher messages. Then in July 1942 the Testery was switched to

breaking Tunny traffic.^1

Alan Turing

Before reminiscing about the breaking of the Tunny code I should like to recall Alan Turing

himself. If it had not been for him everything would have been very different, and I am eternally

grateful to him that I did not have to bring up my children under the Nazis. We would have

entered a dark age of many years—once the Nazis had got you down, they did not let up.

Here is just one example of what life was like under the Nazis. After the war I met a brave

Belgian lady called Madame Jeanty. Her family was one of those who kept a safe house for Allied

airmen, shot down over Europe and trying to make their way back to Britain to fly again. Helen

Jeanty and her husband had a hidey-hole in their house, and had an airman in there one day

when the Gestapo came calling, at the usual time of 6 a.m. They searched the house up and down

but did not find him, and went away. Everybody was delighted and relieved—claps on the back

or whatever the Belgians do. But the Gestapo came back again to find this celebration in pro-

gress. Her husband was arrested and taken away and she never saw him again. That sort of thing

would have happened time and time again here in Britain if the Nazis had managed to invade.

One reason Britain did not fall to the Nazis is that in 1941 Turing broke U-boat Enigma.

The decisive effect he had on the Battle of the Atlantic can be seen from the tonnages sunk. The

tonnages lost to sinkings dropped by 77% after Turing broke into U-boat Enigma in June 1941,

*This chapter was revised by Jack Copeland following Jerry Roberts’ death in March 2014 at the age of 93.