The National Museum of Computing has finished restoring a Tunny machine - a key part of Allied code-cracking during World War II. Tunny machines helped to unscramble Allied interceptions of the encrypted orders Hitler sent to his generals. The rebuild was completed even though almost no circuit diagrams or parts of the original machines survived. Intelligence gathered via code-cracking at Bletchley underpinned the success of Allied operations to end WWII. Restoration work on Tunny at the museum in Bletchley was re-started in 2005 by a team led by computer conservationists John Pether and John Whetter. Mr Pether said the lack of source material made the rebuild challenging. As far as I know there were no original circuit diagrams left, he said. All we had was a few circuit elements drawn up from memory by engineers who worked on the original. The trickiest part of the rebuild, he said, was getting the six timing circuits of the machine working in unison. The Tunny machines, like the Colossus computers they worked alongside, were dismantled and recycled for spare parts after World War II. The first Tunny machine was built in 1942 by mathematician Bill Tutte. He drew up plans for it after analysing intercepted encrypted radio signals Hitler was sending to the Nazi high command. BBC