What I’m about to tell you is absolutely top secret. So secret, that I cannot reveal my name…
It’s early 1941, the war rages on and Winston is not too happy with that lot up at Station X ‘coz so far they haven’t managed to make any headway with the German cypher code called Lorenz.
The Enigma machine with its three or four coding wheels is a walk in the park compared to Lorenz- which has 12. So sophisticated is this tele-printer cypher with its 1.6 million billion combinations that the German High Command and even the Fuhrer himself have been using it to send sensitive messages all over the Reich believing that it cannot be broken. Winston doesn’t understand the complexity of this cypher but he doesn’t care for technicalities, only results. Time is running out, lives are being lost both here and abroad and a solution needs to be found.
By a sheer chance, one of our listening stations intercepts a long message that has been sent twice without changing the coding wheels! This gives the code breakers a way in. One of them, Bill Tutte, devises a brilliant mathematical formula which can reveal the starting position of the key wheels but it has to be repeated continuously on each line of the message until the starting keys are found; doing this manually can take up to 47 years. Clearly we haven’t got 47 years.
So the boffins at Station X build an electromechanical calculating machine to speed up the process… but it keeps breaking down. So they call upon the GPO for help who send their top engineer to fix it. He takes one look at it and decides that he could do better because he believes that he can process the formula electronically. But he cannot articulate his ideas to the top brass so they send him packing- after all what does he know? He’s just a telephone engineer…
Undeterred he returns to the GPO’s research centre at Dollis Hill where he and his team set about the task. They work tirelessly day and night for the next nine months and build a machine using standard telephone exchange equipment and 1500 vacuum tubes, the same as you’d find in a wireless.
It’s coming up to Christmas 1943 when they finally finish. It’s switched on. After a minute or two all the valves emit a pleasing orangey glow and the lights on the console twinkle. They test it using one of the decoded ticker tapes. It works. They test it again and again using different tapes and it still continues to work and they’re astonished to find that it can process 5,000 characters a second. Without knowing it they had just built the word’s first electronic programmable computer.
It’s delivered to Station X and assembled. It’s huge and weighs more than a ton so it’s nicknamed Colossus. Put to work immediately, it starts delivering excellent results, finding the keys within hours, sometimes even minutes.
Now, you’d think the team at the GPO would take a well-earned break for Christmas- do they hell. They set about building Mk2, this time bigger with 2,500 valves and working five times as fast as the original. It joins Mk1 in May ‘44 and, do you know, the first message it decrypts is that Hitler has fallen for the Allies’ deception and so leaves Normandy lightly defended.
To say the least, Winston’s impressed and gives top priority for more Colossi, of which eight are built and put to work before the end of the war. Without this ability to decrypt the Lorenz code who knows how long the war would have continued. And you know something? During this time Jerry has no idea that their messages are being read like a newspaper, sometimes even before the intended recipient.
At the end of the war Winston orders the dismantling of all but two of the Colossi; all the paperwork and blueprints are destroyed (except one set which is given to the Americans). The existence of Colossus is to remain classified indefinitely.
So, who was this person who designed and built Colossus? It wasn’t Alan Turing, he decrypted Enigma. Nor was it any of the other great cryptanalytic minds at Station X; it was in fact a telephone engineer from Abbotts Road, Poplar: Tommy Flowers. Tommy was the son of a bricklayer who, on leaving school and with great hardship, studied for a degree in electrical engineering at night school and then joined the GPO’s telephone division.
After the war Tommy and his team were sworn to secrecy for life and so had to keep schtum when the Americans unveiled the world’s first programmable computer in 1946 based in part on Tommy’s Colossus, and then spent the next 45 years watching the information age unfold without ever being able to contribute to it before the secret was finally declassified by the Americans in the mid –seventies. And even then the Heath government denied its existence.
Now that the secret is out I can tell you that Station X is Bletchley Park and that my name is Mr Jones and I was a GPO engineer.
Today the architecture of all computers can be traced backed to Colossus- It was that great an invention. But there is no memorial to Tommy in Tower Hamlets; his contribution to the war effort goes unnoticed.
Tommy Flowers, the neglected pioneer of the computer age, lived here, 1905-1998.
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