COLOSSUS was one of the world's earliest working programmable electronic digital computers. But it was a special-purpose machine that was really only suited to a narrow range of tasks (for example, it was not capable of performing decimal multiplications).

If you look for information on the internet about the first computer, most of the sites will tell you that it was ENIAC, the computer built by the Americans, and finished after the end of World War Two in 1945. Because COLOSSUS was built during the war, it was top secret, and no-one was allowed to talk about it. Bletchley Park workers, and the spies who trained there from Section X, did not talk about the things that happened there.

The papers about Colossus and all the design specifications were all destroyed at the end of the war. But recently, enthusiasts have managed to rebuild it, and get it working again.

Here is HRH The Duke of Kent turning it on, watched by some of the original people who worked at Bletchley during the war. So, which do you think was the first computer to be built - COLOSSUS or ENIAC?