24/12/2013 12:34 GMT | Updated 23/02/2014 05:59 GMT

Alan Turing: Was He Murdered By the Security Services?

I have this week written to the Prime Minister, David Cameron, urging a new inquiry into the death of the scientist Alan Turing, who has been finally granted a royal pardon for his 1952 conviction for homosexual relations.

Turing is generally believed to have been committed suicide following his conviction and chemical castration. However, the original inquest into his death was perfunctory and inadequate. Although it is said that he died from eating an apple laced with cyanide, the allegedly fatal apple was never tested for cyanide. Moreover, he was in an upbeat mood at the time of his death and making plans for the future - not the typical profile of a person who takes their own life.

A new inquiry is long overdue, even if only to dispel any doubts about the true cause of his death - including speculation that he was murdered by the security services.

Although there is no evidence that Turing was killed by state agents, the fact that this possibility has never been investigated is a major failing. Even if the security services did not kill him, did they pressure him and did this pressure contribute to his suicide?

State murder is unlikely but we know that he was under observation and a person of concern to the security services.

Turing was regarded as a high security risk because of his homosexuality and his expert knowledge of code-breaking, advanced mathematics and computer science. At the time of his death, Britain was gripped by a McCarthyite-style anti-homosexual witch-hunt. Gay people were being hounded out of the armed forces and the civil and foreign services.

In this frenzied homophobic atmosphere, all gay men were regarded as security risks - open to blackmail at a time when homosexuality was illegal and punishable by life imprisonment. Doubts were routinely cast on their loyalty and patriotism, especially following the unmasking of the bisexual and gay spies, respectively Donald Maclean and Guy Burgess.

Turing fell under suspicion. His security clearance was withdrawn and he was barred from further work at the spy agency GCHQ. Was he subjected to MI5 or MI6 surveillance, pressure and threats? It is time we knew the truth.

The security services were certainly fearful that Turing was vulnerable to blackmail and anxious that he might pass information to the Soviets. The British nuclear scientist Klaus Fuchs was convicted in 1950 of assisting the Soviet Union's atomic programme. There was an irrational, paranoid fear that other leading scientists, such as Turing, might also aid the Soviets; in Turing's case possibly as revenge for the way he'd been mistreated.

There is, of course, not a shred of evidence that Turing ever considered betraying Britain. But the fevered minds of security spooks thought otherwise. Enough to kill him? Probably not. But their pressure on him may have pushed him over the edge.

This is why a thorough, comprehensive inquiry is needed. We need to establish for certain what role, if any, the security services played in the run-up to his death.

The other big issue thrown up by Turing's pardon is: why him alone? Singling out Alan for a royal pardon just because he was a great scientist and very famous is wrong. At least 50,000 other men were convicted under the same law. They have never been offered a pardon and will never get one. Selective redress is a bad way to remedy a historic injustice.

An estimated 15,000 men convicted of the same offence as Alan Turing are still alive. They deserve justice too.

An apology and pardon is due to all of the many thousands of men who, like Turing, were convicted of consenting same-sex relationships. These men were criminalised and penalised for victimless behaviour that was not a crime between heterosexual men and women.

The precedent for a mass pardon is the government's granting of a pardon in 2006 to more than 300 soldiers who were executed for alleged cowardice and desertion during World War One. If they can have a pardon, why not gay and bisexual men?

Finally, it is little known that Turing and the other 50,000+ men were convicted under the same 'gross indecency' law that sent Oscar Wilde to prison in 1895. It remained on the statute book until 2003, classified in the penal code under the heading 'unnatural offences.' Likewise, the law against 'buggery', which was legislated in 1533 during the reign of King Henry VIII, was only repealed in 2003.

The criminalisation of homosexuality finally ended in 2003 in England and Wales. It is only since then that we have had a penal code that does not discriminate on the grounds of sexual orientation.