CONTEST: The Tunny Machine Missing Diagrams Question

(WE HAVE A WINNER. DF from Canada.)

UK - 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...

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. (more)

CONTEST: What happened to the original circuit diagrams?

PRIZE: First correct answer wins an autographed copy of "Is My Cell Phone Bugged? Everything you need to know to keep your mobile communications private."