Bletchley Park

On the weekend we went to Bletchley Park, the headquarters of British Intelligence during WWII and where the first programmable computer was invented, essentially kicking of the entire computing age. It’s actually a big mansion with a whole heap of building scattered around the site so it took us a while to work out where we should be going. Eventually we found the main mansion and the start of a guided tour. The tour guide was a pretty classic eccentric historian but with a geeky twist since most of the history of the site is around breaking the German and Japanese radio codes. They were having a Chitty Chitty Bang Bang carnival – it turns out that it and James Bond were written by one of the people who worked at Bletchley Park during the war.

I don’t think the place appealed to Janet much, but I quite enjoyed hearing the stories of how they found the weaknesses in the German encryption. Things like a radio operator missing his girlfriend and always setting the initial state of the engima machine to his girlfriends name instead of making it random, or the German general stationed in the African desert who reported every day without fail that he had nothing to report. For a while it was that one constant message each day that allowed the British to identify that day’s encryption key and then decode every other message that was sent.

They’ve also spent the last 12 years rebuilding the first ever computer and now have it running and on show. The trick is to never turn it off or the valves that do all the computation are far more likely to blow. They’re actually using a number of the original valves from WWII so it’s pretty impressive. Unfortunately, being a secret operation, they didn’t leave good diagrams of the machines they built which is why it took 12 years to rebuild it from a couple of photos and a rough diagram.

I also found it pretty amazing that despite having 9000 people working at Bletchley Park during the war, no one knew it was the intelligence headquarters until the government records were unsealed 30 years later. They actually discovered that one of the women who worked there during the war was still living just down the road and when they called her she told them there was no point in coming round – she didn’t know anything about it which is what she’d been trained to say all those years ago.

The national computer museum is based there too and we spent some time wandering around there. It was kind of odd to find a guy hunched over a BBC Microcomputer like I grew up with, essentially trying to rewrite the operating system. No hard drives then so every time you put in a new floppy disk you had to copy a program on to it so you could list what programs were on the disk and run them. Somewhat disturbingly they also had a mainframe computer from a nuclear power plant that was in use until 2004 – it had 4k of RAM and filled a cabinet about 3m high and 5 or 6m long. Apparently they don’t upgrade nuclear power plants very often.

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