BLETCHLEY, ENGLAND - JUNE 03: Wheels on the Lorenz SZ42 German cipher machine pictured at The National Museum of Computing on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decipher the German Army's Lorenz cipher using the Colossus computer and Tunny machine at the Government Code and cipher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: The Lorenz SZ42 German cipher machine pictured at The National Museum of Computing on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decipher the German Army's Lorenz cipher using the Colossus computer and Tunny machine at the Government Code and cipher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: The Lorenz SZ42 German cypher machine pictured at The National Museum of Computing on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decypher the German Army's Lorenz cypher using the Colossus computer and Tunny machine at the Government Code and Cypher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: The Colossus computer, used during World War II to decypher German code at Block H, Bletchley Park pictured at The National Museum of Computing on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decypher the German Army's Lorenz cypher using the Colossus computer and Tunny machine at the Government Code and Cypher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: An oscilloscope linked to a Colossus computer, used during World War II at Block H, Bletchley Park pictured at The National Museum of Computing on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decypher the German Army's Lorenz cypher using the Colossus computer and Tunny machine at the Government Code and Cypher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: Operations Director at The National Museum of Computing Victoria Alexander demonstrates how the Tunny Machine was used during World War II at Block H, Bletchley Park on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decypher the German Army's Lorenz cypher using the Colossus computer and Tunny machine at the Government Code and Cypher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: Operations Director at The National Museum of Computing Victoria Alexander demonstrates how the Tunny Machine was used during World War II at Block H, Bletchley Park on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decypher the German Army's Lorenz cypher using the Colossus computer and Tunny machine at the Government Code and Cypher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)

BLETCHLEY, ENGLAND - JUNE 03: Former "Wrens" - members of the Women's Royal Naval Service and codebreakers at Bletchley Park, (L-R) Irene Dixon, Lorna Cockayne, Shirley Wheeldon, Joanna Chorley and Margaret Mortimer pictured in front of a Colossus computer at The National Museum of Computing on June 3, 2016 in Bletchley, England. During World War II British codebreakers helped decypher the German Army's Lorenz cypher using the Colossus computer and Tunny machine at the Government Code and Cypher School's (GC&CS) main codebreaking centre, Bletchley Park. The machines at Bletchley Park's Block H, the world's first purpose-built computer centre, helped gather crucial intelligence for the British military during the war. (Photo by Jack Taylor/Getty Images)