A gay man who was convicted of buggery 51 years ago is fighting to clear his name and have the conviction removed from his criminal record.

John Crawford, a retired butler from London, was convicted in 1959 aged 19 for having consensual sex with another man.

He told the Guardian he made a confession to the crime after being held in a cell and beaten for a week.

Although the law began to change in 1967, it was not until 2004 when gay people were given completely equal sexual rights.

Mr Crawford said he discovered the conviction remained on the police national computer (PNC) when he applied for a job as volunteer at Wormwood Scrubs prison eight years ago.

He told the newspaper: “I saw John Crawford. 1959. Charged on two counts of buggery. Since then, I’ve analysed my life and found out the amount of my jobs that I’ve lost because I’ve got a criminal record.”

Mr Crawford must mention the conviction every time he applies to do volunteer work. Although Hampshire police agreed to treat him as an “exceptional” case and delete his record from the PNC last month, he must still admit the conviction when applying to work with vulnerable people.

He said: “What I want to do is apply for voluntary work and, when it comes to the box on the application form that says ‘do you have a criminal record’, I want to be able to say no.”

His lawyers have informed the justice secretary, Jack Straw, that the rules must be changed or they will initiate judicial review proceedings at the high court to challenge the Rehabilitation of Offenders Exceptions Order 1975.

This means those working with vulnerable people must disclose their conviction history, even if the record is spent or deleted.

They will argue that Mr Crawford’s sexual orientation continues to be criminalised under the existing system and that it “condones” his original conviction.

Last year, prime minister Gordon Brown made a formal posthumous apology to gay mathematician Alan Turing.

Turing was convicted of homosexuality in the 1950s. He lost the right to continue his code-breaking work and subsequently killed himself after undergoing brutal hormone treatment.

Some critics welcomed the apology but said the estimated 100,000 other British men who were convicted of homosexuality offences should also receive similar recognition.