IT HAS the bulk to challenge a Chippendale sideboard and a heartbeat of clicks, whirrs and hums that conjure up a supercharged sewing machine, so it is difficult to imagine that a Turing bombe is a distant but direct ancestor of the laptop.

Volunteers at Bletchley Park, the museum based on Britain’s wartime codebreaking centre in Buckinghamshire, have reconstructed from scratch one of the vast and complex electro-mechanical decoders — all electric motors, gearboxes, 108 spinning drums and miles of cable — that broke the German Enigma machine.

They tried it yesterday, and it worked. They fed in a known coded message and it came up with the right answer. Much work remains, however, before it goes on permanent public exhibition next July.

More than 7ft long, 6ft high and weighing more than a ton, the first machine was installed in 1940 in Hut No 1 – long since demolished – in the Bletchley Park grounds. By 1945 more than 200 of them were analysing German military radio traffic, searching millions of combinations of coded letters until they found something that made sense.

Their finest hour is regarded as intercepting messages to U-boats, a crucial factor in winning the Battle of the Atlantic. Some historians believe that Bletchley Park’s work shortened the war by two years. The codebreakers were able to read in minutes what had previously taken weeks.

The bombe system was developed by Polish scientists who invented a “cryptological bomb” after being given an early captured Enigma machine. It was refined by Alan Turing and Gordon Welchman, two brilliant Cambridge mathematicians. Their theories were made reality by the British Tabulating Machine Company (later ICL Computers), of Letchworth, Hertfordshire, which built the devices.

Simon Greenish, director of the Bletchley Park Trust, believes that the Turing bombe is a true progenitor of the modern computer.

“The bombe was an electro-mechanical device,” he said. “But it led directly to the next generation of Bletchley Park decoding machines, Colossus, which was the first to use valves, and to use them as switches rather than amplifiers. It was the first true computer. It had no memory but it could do calculations as fast as today’s Pentium processor.”

At the end of the war, Churchill ordered all but a few machines destroyed. The survivors were used to decode Warsaw Pact signal traffic in the early years of the Cold War. The bombe and its successor machines remained secret until the mid-1990s.

Explore UK News

• Crime News

• Education News

• Health News

• Scotland News

Times Recommends

• Foxy Knoxy snared by her lust and her lies
• Britain is the land of the shrinking family
• Zac Goldsmith: Not such a green god