BLETCHLEY, ENGLAND - JUNE 03: Commercial Director at The National Museum of Computing Jacqui Garrad poses with a Colossus computer, 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: Commercial Director at The National Museum of Computing Jacqui Garrad demonstrates how the Colossus computer 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: Commercial Director at The National Museum of Computing Jacqui Garrad demonstrates how the Colossus computer 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: Wires on the back of a Tunny Machine, used to decode cypher 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: Commercial Director at The National Museum of Computing Jacqui Garrad demonstrates how the Colossus computer 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)