This is a little off the usual topics, but I hope you will enjoy it anyway… and my apologies if you can’t see the content in question because of copyright or time constraints. The BBC’s Timewatch series broadcast a documentary yesterday (available here, for another 10 days or so from today) about Bletchley Park’s WW2 code-breakers… but before you say “yeah, yeah, Enigma, Turing, blah blah, hasn’t that story already been told?”, bear with me. Enigma and Turing are mentioned, yes, but this was actually about the cracking of the Lorenz encryption system, also known as “Tunny”. In fact, among other things, the programme was a useful reminder that the Enigma machine was actually a very cumbersome way to go about things. For all its mechanical brilliance, it was strictly an “off-line” encoding and decoding tool. It required a team of three per machine to operate: one to key in the cleartext, another to read and note down the output, and a third to send the ciphertext (and, of course, the corresponding team of three at the receving end).
I’m not going to go into the details of Enigma or Lorenz here – if you want more than is in the BBC programme, I highly recommend this article by the late Tony Sale (of whom more in a moment). What I did want to do, though, was mention some of the fascinating inferences which lurked between the lines of the Tunny narrative.
For instance, at one point in the documentary it is noted that interception of Hitler’s top-echelon signal traffic helped the Allies do what we would now think of as ‘profiling’ – working out the quirks of his behaviour, and crucially, the ways in which he was likely to diverge from expected military strategies.
The story also hinted at the far broader implications of Churchill’s reported decision to destroy Bletchley’s ground-breaking electronic computing machines – the first of their kind in the world. For decades, the story was simply that Churchill had ordered the machines destroyed and their existence to be kept secret… and that it wasn’t until Tony Sale and others reconstructed one that Colossus ran again, after 60 years of oblivion. It emerges, though, that a couple were in fact kept in operation and used to underpin Cold War code-breaking efforts. In other words, Churchill’s decision wasn’t simply a matter of good secret-keeping for its own sake, but a strategic move to preserve a cryptanalysis advantage for the post-war period.
If that decision paid off over time, it was certainly not without cost. For the “unsung heroes” of the title – principally Tommy Flowers (the telecoms and computing engineer) and Bill Tutte (the mathematician and cryptanalyst), it meant a lifetime of obscurity and zero recognition of their achievements. The documentary also describes how Flowers appears single-handedly to have conceived and designed Colossus with no encouragement or resources from his military employers… only to have them turn round and ask for four more (on the double!) once the device’s utility became apparent.
For the economy as a whole, Churchill’s choice may well have meant that the UK forfeited the opportunity to capitalise commercially, from the outset, on its pioneering work in electronic computing. Whether Churchill was conscious of balancing the security and intelligence dividend against the broader economic cost of secrecy, we may never find out.
In the late 90s I visited Bletchley Park and was lucky enough to be shown round in a group led by Tony Sale. He wore his expertise lightly and with self-effacing modesty. Indeed, it wasn’t until quite a while later that I learned who our softly-spoken guide had been, and how significant his role was in preserving the site and its unique history. It seems Bletchley Park has that effect on people.
Tommy Flowers 1905-1998
Bill Tutte – 1917-2002
Tony Sale – 1931-2011
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