I had the opportunity to visit Bletchley Park a few weeks ago for an XMLUK members conference and while there had a chance to look over the Colossus Mark II computer that is being restored there. On the day that I visited it was actually up and running, which was an extra bonus.
Sounds all very geekish, but as someone who work on his first computer in 1967, it certainly was very interesting to see some of the foundations of what should have been the start of a dominant British Computer Industry. Sadly with the burning of the Colossus blueprints and the destruction of the all of the machines after WWII, and the gifts of various computer technology to the USA, that was not to be.
However, thanks must go to the team of enthusiasts including Tony Sale, Cliff Horrocks, David Stanley and many other who have struggled and in the end very successfully managed to rebuild one of these machines and get it running again. The full story of that rebuild can be found here.
Some reference sites that talk about the history and background to the Colossus project.
Beasley's Place 