Photos: The Colossus WWII codebreaking machine

This is the rebuilt Colossus Mk II computer at Bletchley Park's National Museum of Computing.

The original Colossus machine was built using more than 1,500 valves by Post Office engineer Tommy Flowers to speed up the breaking of German codes - in particular that of the Lorenz cipher.

The very existence of Colossus was kept secret as its success relied on the German's not knowing that the code could be broken.

At the end of the war destruction of most of the Colossus machines was ordered because of the secrecy around the machines, while the blueprints were burnt in a furnace – although contrary to popular belief it was not Winston Churchill who ordered the Colossus machines to be dismantled..

The machine pictured here was painstakingly rebuilt over 14 years by computer expert and former spy Tony Sale, who collected valves from decommissioned BT exchanges.

Photo Credit: Andy McCue

See more photos from Colossus here…