Colossus: The First Computer by Manda Scott

I am watching the first flurry of 2013 snow spin down outside the winter and very glad that we have central heating. And that the dog is with my step daughter and is not pleading to go out, regardless of the temperature or conditions outside.

I am reminded also, of the 108 year old lady who died in our village recently, and her stories of how, as a child, she was sent up into the south Shropshire hills to collect blaeberries (blueberries or bilberries to the southerners around here)  - if she didn’t collect enough, she didn’t get her winter shoes.  But whatever the state of her footwear, she still walked the five miles down ‘Muddy Lane’ and over the hill to school in the neighbouring village every morning and back again in the evening. The lane was a river during the recent floods, and most mornings, it’s a wellie-sucking nightmare of freezing, slushy mud.

Every morning I walk there, I think of Elsie, and am glad of modern footwear, and the car drive with my father that took me to school in the morning.  Granted it was a good thirty eight miles, but we were warm and dry and the train, then train, then bus ride home in the evenings wasn’t nearly as bad as I imagined at the time.  The waiting at freezing bus stops was nothing compared to trudging through freezing mud.

Bill Tutte (photo from Wikipedia)

All of which leads me to  WT (Bill) Tutte, a Suffolk lad, son William John senior (can we hope that one day, men are going to stop naming their sons after themselves?) of an estate gardner and Annie Tutte, née Newell, a cook and housekeeper.  The family moved around in his youth, but when he was five, they moved to Cheveley, a village just outside Newmarket, while his father took up a position at the Rutland Arms Hotel in the town.  Bill was a bright lad at primary school and won a scholarship to Cambridge and County Day School – which was twelve miles away.  Several of his biographies tell that he had to ‘make his own way’ to the school (and back) daily; none of them has ever enlightened me as to how he achieved this, but I imagine it makes Elsie’s trudge over the Clee hill pale by comparison: I used to live in the next village along to Cheveley and one of my main clients when I was a young stud vet was the Chevely Park stud: it’s a beautiful place, but there’s not a lot between Newmarket and the Urals when the wind is easterly and it can be bitterly cold.

Nevertheless, the young Bill went on to read Chemistry at Trinity College, Cambridge, although his interest in mathematics was such that he published a paper with four friends on the problem of  ‘Squaring the Square’ (For those with a mathematical bent, the problem was described in the book ‘The Canterbury puzzle and other tales’ and involves decomposing a rectangle into squares, each with sides of different integer lengths.  Tutte and his three friends described the rectangle as a graph and the graph as a circuit with resistors connected to their top and bottom edges and then described the flow of an electrical current through the graph-circuit.

Bill was studying for a post-graduate degree in Chemistry when the Second World War broke out and it became imperative to decipher the Axis military communications.  The powers that be were coming round to the idea that they needed mathematicians more than the linguists who had broken previous ciphers and soon Bletchley Park sent out a quiet word to senior academics in Oxford and Cambridge to keep an eye out for young men (exclusively) of a mathematical bent who might be prepared to enlist in the secret never-to-be-spoken world of the cryptanalysts.

Originally rejected by Alan Turing’s team, Bill was ultimately recruited by John Tiltman who headed the research station, and came to Bletchley Park in January 1941.   Soon after, he was handed a copy of the newly intercepted LORENZ teleprinter (‘Geheimschreiber’) cipher to see what he could make of it. Considerably more complex than the ENIGMA ciphers, the LORENZ code had so far proved entirely intractable.  Given that it was the code used by the Nazi military command to distribute comments, orders of battle and progress updates to and from their headquarters in Berlin, cracking it was vital to the Allied war effort.

Alan Turing and the team that broke the Enigma codes had the advantage of a real machine to examine and a background of Polish work that had contributed in a large part to the early cryptanalysis.

Bill’s team never had any access to a Geheimschreiber machine and had to achieve the complete analysis based on an understanding of German military language and sheer raw  statistics.

Bill’s colleague, Captain Jerry Roberts, described him a spending hours sitting at his desk, staring into space. “I used to wonder if he was doing anything, but my goodness he was.  Breaking [it] was a most extraordinary achievement.” 

Photograph of Geheimschreiber from Wikipedia

The breakthrough came in August of  1941 when a German operator made the fundamental error of sending the same message twice in a row, but used an abbreviation for an early word, thus allowing the cryptanalysts some insight into its nature.  It still took four months, further ‘depth’ transmissions, an increase in the accuracy of the ‘Y’ listening stations and many hours of advanced statistical analysis, but Bill Tutte lead the team that unlocked the mathematics of the cipher and thus was able to describe the twelve-wheel machine that was creating it.

It became swiftly clear that without mistakes on the part of the enemy operators, no transmission would be deciphered, and that four months from transmission to reading was too long.  This is where Tommy Flowers comes into the story of the first computer.  Bill Tutte developed the statistics, but Tommy Flowers, an east end lad who had progressed through the GPO’s engineer training scheme and had worked with Alan Turing on devising an electro-mechanical method of breaking the Enigma ciphers.   

Brought in to work on the Lorenz ciphers, Tommy devised and built the COLOSSUS: the first fully electronic computer.  He did it against the overwhelming theories of those around him (who resented his use of thermionic valves) and funded the first Colossus largely on his own.  Having proved itself, ten models were commissioned, each one more complex than its predecessor and an eleventh was in production when the war ended.  Capable of the (then) astonishing speed of 2000 calculations per second, each involving up to 100 Boolean calculations on 5 separate streams.

The Colossus machine (photo from Wikipedia)

Much of the post-statistical analysis had to be done by hand and the operators – many of whom were young women with a flair for mathematics became adept at reading the results and reconfiguring the machine to test for other analyses so that the cryptanalysis moved more swiftly.

The first real-time use of Colossus came in the battle of Kursk in which Stalin was not only informed of the Nazi intent to attack, but given the entire order of battle verbatim. The subsequent defeat of Hitler’s troops was a crucial turning point in the war on the eastern front.

By the closing stages of the war, the team at Bletchley was able to hand General Eisenhower a print out of Hitler’s response to the preparations for D-Day, thus triggering the final command to commit the troops as planned.

Bill Tutte lecturing in Canada (Photo from Wikipedia)

Bill Tutte, the boy who made his own way twelve miles to school and back each day, was never decorated for his work in Bletchley Park although others since have described it as ‘the greatest intellectual achievement of the twentieth century’.  Never the less, he was elected a Fellow of the Royal Society and later, having attained his PhD at Cambridge and moved to Canada, he was made an Officer of Canada.  His work was classified for many years, but, unlike many at Bletchley, he lived long enough to be able to talk about it.  His lecture ‘FISH and I’ makes fascinating and inspiring reading. 

Bill Tutte died in 2002 an acknowledged hero, but one whose name deserves far more widespread recognition.