Silicon Valley joined the campaign to save Bletchley Park yesterday, when two US technology companies made a $100,000 (£56,000) donation and urged others to repay “a debt that is owed by everyone in the IT industry today”.

The National Museum of Computing, which is housed at the site where the German Enigma cipher was broken by early decryption machines during the Second World War, wants to raise £7 million to secure its collection of pioneering computers.

The campaign began after the deteriorating conditions at the site were decried by the country's leading computer scientists in a letter to The Times in July.

Among the collection at the museum — which is staffed by 40 volunteers, free to visit and receives no public money for its upkeep — is the Colossus computer, which played a key role in cracking Enigma.

Phil Dunkelberger, the president and CEO of PGP Corporation, a leading encryption specialist that donated $50,000, as did IBM, the computer group, described Bletchley Park yesterday as the “first step to Silicon Valley”.

He said that today's efforts to fight cybercrime, identity theft and online terrorism owed everything to the understanding of the theory and practice of encryption developed there during the war.

“Stealing identities and cybercrime — this is all tied back to what Bletchley was built for,” he told The Times yesterday. “A lot of the principal work by these guys is just as valid today.” Mr Dunkelberger said that the industry around the world needed to be aware of its heritage and to heed the “clarion call” to come to the aid of Bletchley.

He added: “To paraphrase Churchill, it's a place where the intellectual capacities of a few have so benefited the many.”

Simon Greenish, the director of the Bletchley Park Trust, said that the letter to The Times had energised efforts to save the site. “Undoubtedly the letter has raised the profile considerably,” he said.

“It's helped catalyse the process, as a lot of people were unaware of what was happening.” Visitor numbers have also increased, with a record 3,500 people visiting on Bank Holiday Monday.

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