Secret Life of Bletchley Park - McKay Sinclair [119]
Max Newman was a marvellous fellow and I always sort of felt grateful to have known him … we used to have tea parties … which were mathematical discussions of problems, developments, techniques … a topic would be written on the blackboard and all of the analysts, including Newman, would come, tea in hand, and chew it around, and see whether it would be useful for cracking codes.3
As well as Enigma, German High Command was now making use of Lorenz teleprinter machines to transmit encrypted messages. These used the Baudot Murray system, a series of holes (though not Morse) punched through tape, each series of five in different configurations representing a different letter of the alphabet. What made these communications – which became known around Bletchley Park as ‘Fish’ or ‘Tunny’ – particularly crucial was that many of them involved messages sent to and from German High Command. These were not merely communications between men out in the field; they were communications between generals and orders from the Führer himself.
The breakthrough on this complex system was made by a young chemist/mathematician called W.T. Tutte. In the meantime Alan Turing, having returned from several months in the USA, eagerly dived into discussions on the subject, having spent his voyage back reading up on the science of electronic circuits. Turing spent many weeks formulating methods through which the thing could be cracked; these were referred to as ‘Turingismus’. Also present at Bletchley Park was one Dr Charles Wynn-Williams, a circuit expert brought in from radar research who had the wherewithal to build digital circuitry with electronic valves that could switch a thousand times faster than a relay.
It was at this point that the expertise of the Dollis Hill Post Office Research Station was called upon. Dollis Hill is a pleasant suburb of north-west London that overlooks Wembley and from which central London can be seen in the distance. The establishment in question – which also played host to an underground bunker for Churchill’s use – was at the top of the hill. It was here that Tommy Flowers was based. Along with Wynn-Williams, Flowers began work on constructing a machine known – rather sweetly – as the ‘Heath Robinson’.
Looking precisely like the sort of zany contraption that one of William Heath Robinson’s illustrated inventors might contrive, this machine has been described by some veterans as being ‘held together with elastic and bits of string’. However, no matter how comical it may have looked, it could run teleprinter tapes at high speed, like a super-fast bombe, at a rate of over 1,000 characters a second. It was this machine that was to pave the way for its successor, Colossus.
The Heath Robinson did its level best, especially given the exceptional nature of its speed. It demonstrated that it could be used to find the settings on one bank of the ‘Tunny’ code wheels. While it proved possible to break such codes manually, the velocity of the machine meant that more were ordered; soon, Bletchley had twelve improved models.
Despite the machine’s assistance, however, the work was still laborious. ‘They [the Hut] would put the message to be broken on the table and if you failed to break it, you’d put it on a pile and then somebody else could have a go at it,’ says Captain Jerry Roberts. ‘And if they broke it, well and good.
‘But that pile of the non-broken messages, the dead ducks, was never big. I deduced from this that we were breaking certainly better than ninety per cent of what we were being given to break.
‘It certainly did require patience but also don’t forget if you’re having a high success rate, even if it took you four, five, eight hours to break a day’s traffic, the reward was very great because you could decipher a lot more messages using the information you’d discovered.’
And it could be a dispiriting business. A slightly