My Lords, on 6 August 1885, late at night in the Commons debate on the Criminal Law Amendment Act, Henry Labouchère suddenly produced an amendment to the Bill before the House. This amendment criminalised homosexual acts. The only discussion was over the penalty to be imposed. Labouchère had proposed a maximum of one year. Sir Henry James suggested two years and Labouchère agreed. The whole debate had four speakers, including Labouchère. It lasted four minutes and consisted of a total of 440 words, but 75,000 men were convicted under this amendment, and Alan Turing was one of those.

Sixteen thousand of those men are still alive, and under the terms of the Protection of Freedoms Act which we passed last year, they can all now apply to have their convictions disregarded. This will provide real comfort for them, their families, their relatives and their loved ones and will help to put right a little a serious historical injustice. As the Protection of Freedoms Bill went through this House, I tried to amend it to extend this disregard posthumously to the 49,000 men similarly convicted but now dead. I felt strongly that we should provide the same comfort and partial rehabilitation to the families, friends and loved ones of those convicted but now dead as we have to those convicted but still alive.

The Government did not agree with us. They pointed out that, among other things, it would not always be possible in very old cases to know when sexual activity was non-consensual or under age. I think that the Government were wrong then and I think that they are wrong now. I think that it would be simple to grant a posthumous disregard only when the applicants can provide compelling evidence that there was consensual, age-of-consent sexual activity involved, but the Government were firm.

I then turned to the issue of a pardon for Alan Turing. It seemed to me that if we could persuade the Government that this was the right thing to do, it would be a symbolic first step towards a disregard for the 49,000 others convicted and now dead, and perhaps a step forward towards successfully amending the Protection of Freedoms Act to that effect when the opportunity arises. I knew about Turing. Turing only ever had one doctoral student. This was a man called Robin Gandy, who was Turing's closest friend and the executor of his will. Robin Gandy taught me mathematics when I was an undergraduate at Manchester University in the 1960s, and I was familiar with the Turing story from an early age. However, the Government were not to be persuaded about a pardon for Turing. The Government, like their predecessor, acknowledged Turing's contribution to the war effort at Bletchley Park, they acknowledged his contribution to computing and they acknowledged the injustice and terrible cruelty of what was done to him. They were absolutely right to acknowledge all these things. They are all true.

Turing led the way in cracking the Enigma code. This alone probably turned the Battle of the Atlantic. Respected commentators estimate that this shortened the war by two years, saving many, many thousands, perhaps even hundreds of thousands of lives. This was Turing's work. Turing is also one of the fathers, if not the father, of computer science. Every time anyone, anywhere, uses a computer for any purpose there is a kind of debt to Turing. And Turing was treated with terrible cruelty, as were all convicted under the Labouchère amendment.

My noble friend Lord McNally said in February last year:

“It is tragic that Alan Turing was convicted of an offence which now seems both cruel and absurd—particularly poignant given his outstanding contribution to the war effort”.—[Official Report, 2/2/12; col. WA341.].

However, the Government could not be persuaded to exercise the royal prerogative of mercy in Turing's case. They argued that a posthumous pardon was not considered appropriate as Alan Turing was properly convicted of what at the time was a criminal offence. He would have known, they argued, that his offence was against the law and would be prosecuted. This is not a strong argument. The royal prerogative of mercy has been exercised quite recently in exactly these conditions.

As part of the Good Friday Agreement in Northern Ireland, 18 convicted terrorists, some of them murderers, were granted pardons. These people were presumably aware that their offences were against the law and would be prosecuted. And everyone acknowledges that the previous Government had bravely and rightly granted a statutory pardon to all those British soldiers—304 of them—executed in the First World War for what were then seen as military crimes. So it was suggested that it would be better trying to pursue a parliamentary pardon, a statutory pardon, rather than pressing the Government to exercise the royal prerogative of mercy. That is what this Bill sets out to do.

People recognise that Turing was a hero and a very great man. As long ago as 1999, Time magazine named Turing as one of the 100 most important people of the 20th century. In 2002, Turing was ranked 21st in the BBC’s poll of the 100 greatest Britons. Last year, in the centenary of Turing’s birth, there were a very large number of events all over the world celebrating Turing's life and his achievements. More than 40 countries were involved in those celebrations.

Here in the UK, there were a large number of events, including an exhibition on his work and times at the Science Museum, now extended by popular demand until October this year. The Royal Mail issued a commemorative stamp and in March, Turing's universal machine—the theoretical basis for all computers everywhere—was voted the greatest British invention of the 20th century. The head of GCHQ, Sir Iain Lobban, said publicly that,

“we should remember that the cost of intolerance towards Alan Turing was his loss to the nation”.

Last September, the Information Commissioner's Office inaugurated the Alan Turing lecture series. The first lecture was delivered by Professor Christopher Andrew, the official historian of M15, who spoke of Turing's greatness and his inexcusable persecution. Last year, Turing's papers were saved for the nation by a last-minute Intervention by the National Heritage Memorial Fund, which made a donation of £200,000.

There is now a statue of Turing in Manchester, where he lived, worked and died. There is now a statue of Turing in Paddington, where he lived for a while. The statue stands alongside statues of Mary Seacole and Paddington Bear. All three statues were voted for by the residents and it strikes me as a peculiarly and encouragingly British set of choices.

At the end of last year a group of very distinguished scientists and mathematicians and Members of this House wrote to the Telegraph asking the Prime Minister to pardon Alan Turing. This letter was signed by Professor Stephen Hawking, Sir Paul Nurse, president of the Royal Society, Dr Douglas Gurr, chair of the Science Museum Group and Sir Timothy Gowers, the Rouse Ball Professor of Mathematics at the University of Cambridge. The letter was also signed by, among other Peers, the noble Lords, Lord Faulkner and Lord Rees of Ludlow and the noble Baroness, Lady Trumpington. I am very glad to see them in their places today and very much look forward to hearing them speak in a few moments.

There has also been a successful musical of Turing's life, and next year at the Barbican there will be the world premiere of a new choral work celebrating his life, composed by James McCarthy and commissioned by the Hertfordshire Chorus. Soon there is to be a new film of Turing's life. Benedict Cumberbatch is to play Turing and Keira Knightley is to play his girlfriend—which might seem a little odd, because of course, Turing was gay, and it was because he was gay that he was treated so appalling by the Government of the day.

As I think everybody knows, he was convicted in 1952 of gross indecency and sentenced to chemical castration. He committed suicide two years later.

The Government know that Turing was a hero and a very great man. They acknowledge that he was cruelly treated. They must have seen the esteem in which he is held here and around the world.

There are two quotations which, for me, sum up Turing's greatness and establish him as a British hero. The first is from Professor Jack Good, who was at Bletchley Park with Turing and who died last year at the age of 91. Professor Good said that,

“it was a good thing the authorities hadn’t known Turing was a homosexual during the war, because if they had, they would have fired him .... and we would have lost”.

The second quote is from the very distinguished Harvard professor Steve Pinker in his book The Better Angels of Our Nature. Professor Pinker says:

“It would be an exaggeration to say that the British mathematician Alan Turing explained the nature of logical and mathematical reasoning, invented the digital computer, solved the mind-body problem and saved Western Civilization. But it would not be much of an exaggeration”.

It is not too late for the Government to pardon Alan Turing. It is not too late for the Government to grant a disregard for all those gay men convicted under the dreadful Labouchère amendment and similar Acts. I hope that the Government are thinking very hard about doing both those things. But while they are thinking, Parliament can act. We can start by granting a pardon to Turing, and we can continue by finding a way to amend the Protection of Freedoms Act to extend the disregard to all who were treated as cruelly as Turing was simply for being gay. We can start that process today with this Bill, and I beg to move.