Codebreaking Tunny machine rebuilt for Bletchley Park

Video caption, The working replica of the Tunny machine in action

A World War II code breaking machine has been reconstructed for a gallery at Bletchley Park in Milton Keynes.

The Tunny machine has been recreated from diagrams and photographs.

The machine was used to break encrypted messages by the Germans and is credited with providing key pieces of intelligence to Allied forces.

It has gone on display as part of an exhibition in the new Tunny Gallery at the National Museum of Computing at Bletchley Park.

The machine was named Tunny by cryptographers.

Towards the end of the war, up to 15 of the codebreaking machines were in use at Bletchley Park providing the final decryption of around 300 messages a week.

The development of the Colossus machine in 1944, now recognised as the first modern computer, further helped the work of the Tunny, reducing the time spent deciphering messages from several weeks to up to four days.

The Tunny machines were dismantled and recycled after the war.

A team led by National Computing Museum volunteers rebuilt the machine.