Colossus in 1944/5

By the end of the war, ten Colossus machines were working around the clock to find the start wheels of the Lorenz-encrypted messages. They made a huge impact by accelerating the code-breaking and enabling many more messages to be deciphered. It is sometimes said that the Allies may have been able to read some messages even before Hitler's generals had seen them.

The Colossi were operated by WRNS and this photograph, top secret for 30 years, is one of the few existing images of the original computers.