Stella Barrow (nee Binnie)

I arrived at Eastcote in September 1944 shortly after my last term at school. On joining the WRNS I had been given no other option apart from going to Eastcote, and the only information vouchsafed was that it involved operating ‘light machinery’. On arrival we were given a pep talk about the type of work we would be doing, that we were an outstation for Bletchley Park (Station X) where all the vital decoding (Ultra) took place and that absolute silence about everything we knew and did must be maintained at all times. We signed the Official Secrets Act.

At Eastcote there were four watches: A, B, C and D (I was on A watch) working round the clock in eight-hour shifts, each watch working a different shift for one week. After the last night of the night watch which ended at 0800, and following Divisions on the ‘quarter-deck’ (part of the concrete drive with a flagpole in the middle – ‘Get your lorry off the quarter-deck’ an irate Wren officer would bellow to a bemused driver) we collected our pay (£4-5 per month), slept if we could in our ‘cabins’ – noisy with off-duty Wrens – before going back on watch at 1600 until midnight. The following morning we went on four day’s leave.

The bombes on which we worked were all operated by Wrens, either at Bletchley Park or at one of the outstations. They were large machines devised by Alan Turing to break German codes encrypted on Enigma machines. The German Enigma was a sophisticated kind of typewriter with three interchangeable wheels (naval enigma had four, the fourth rotor being added, when required, to the existing three) and twenty-six settings (A-Z) which, when set with the day’s code, would scramble all typed messages, thereby giving literally millions upon millions of permutations every day. Very fortunately, the Poles, a fortnight before they were invaded by Germany on September 1st 1939, had handed over a German Enigma and all the information they had to representatives from Bletchley Park. With this priceless gift, Alan Turing, a brilliant Cambridge mathematician, was able to work out a system for cracking the complex Enigma. The bombe was the result.

Roughly the chain of operations was as follows: listening stations known as ‘Y’ stations picked up radio messages which were passed on by despatch riders or by teleprinter to Bletchley where they were sorted and allocated to the appropriate Huts (Naval, Military, Air Force, etc.) Here they were made into ‘menus’. These menus were the outcome of a combination of innate mathematical skills, ‘cribs’ (previously acquired knowledge) and hunches of the Bletchley cryptanalysts, and took the form of diagrams showing the possible rotor wheel order and settings of the Enigma machines. Working in pairs we followed the menu instructions, placing the colour-coded drums (the possible rotor order) in three banks on the front of the bombe, and positioning them according to the given three letters setting on the menu; finally we plugged in the complex wiring at the back, switched on the bombe and hoped for the best.

The three banks of drums whirred round at different speeds testing every possible permutation of that particular setting. Using electrical wizardry which I don’t begin to understand, the bombe might give a ‘stop’. The new setting would be tested on our small Enigma-type machine. If we thought there was any chance of this setting providing the code for that day, it was immediately teleprinted back to Bletchley. If successful (seldom) and of importance, the original message would then be decrypted, translated and transmitted to a Liaison Officer from the highly secret SLU (Special Liaison Unit, part of M16) attached to one of the Command Headquarters. Here the field commander would read and memorise the information, hand it back, after which it was immediately destroyed.

The Germans changed the rotor order and settings every twenty-four hours at midnight and as there were different codes for the three services, the Germans (apart from Admiral Dönitz) were convinced that their codes were unbreakable. A lot of subterfuge was involved to maintain this belief: e.g. reconnaissance planes sent up to ‘spot’ a convoy or appreciative thanks to a fake spy for his ‘valuable information’.

Information supplied by Ultra in 1940 to Air Chief Marshal Sir Hugh Dowding and used by him to deploy the RAF (The Few) to best advantage against the numerically superior Luftwaffe helped win the Battle of Britain. Operation Sealion was abandoned in September and the threat of invasion was over. The ongoing Battle of the Atlantic in which thousands of merchant ships bringing supplies to Britain were sunk by U-boat wolf packs, was brought eventually to a successful conclusion with information from Ultra which had had to struggle for ten months to break the naval codes. One unexpected bit of good luck was the retrieval of an Enigma and, in particular, the naval codes from a U-boat before it sank. At El Alamein, General Montgomery received vital help from a small bored German outpost which at midnight, when the army codes for the day changed, always sent out the same message, ‘Nothing to report’. As a result Bletchley cracked the codes before the intended recipient had read the message. Information from Ultra before D-Day assured the Allies that Germany was prepared for the Allied landings to be at the Pas de Calais and not Normandy; all the bogus airfields, planes, tanks and apparent troop movements had deceived them. It is generally conceded that the massive and invaluable information from Bletchley Park shortened the war by up to two years. Many people (General Eisenhower for one) would go further and state categorically that without Ultra the outcome of the war might have been very different.

Our work at Eastcote wasn’t arduous or difficult, just frustrating. The bombes often broke down (short-circuiting seemed to be the main trouble) and had to be revived by RAF technicians. We never knew, obviously, what code we were working on and had to rely on newspaper cuttings pinned up on the notice board giving news of an Allied success which we presumed was partly attributable to Ultra. It wasn’t a glamorous job and I don’t suppose any of us would have chosen it, but now, after sixty-four years, I am pleased to have been one of the Winston Churchill’s many thousands of ‘geese which never cackled’ – but only the Bletchley boffins actually laid ‘the golden eggs’. And memorably, the world’s first computer, the Colossus, operated there.

After the war all the bombes, together with all information connected with Bletchley Park, were destroyed. There was little recognition by the Government for the outstanding work done by the cryptanalysts, let alone the Poles who had given the original German Enigma.