The revelations about the Americans’ torture of terror suspects have rightly caused outrage across the world.

The U.S. government has owned up to the shadow of institutionalised brutality that has hung over ‘The Land Of The Free’ since the inception of the War On Terror after 9/11.

The sense of disquiet should extend to the political establishment in Britain, given the mounting evidence that our own intelligence and security agencies may have colluded with the CIA in rendition, torture and a disregard for international human rights law including the Geneva Conventions.

Nothing illustrates our own national disgrace more graphically than the case of Shaker Aamer, a 46-year-old family man from London, who has now been held for almost 13 years in the notorious detention camp at Guantanamo Bay, having been seized by the U.S. military in Afghanistan in November 2001.

Shaker Aamer has been held without charge at the Guantanamo Bay detention facility since 2002

During Mr Aamer’s long spell of incarceration, he has never been put on trial or even had any charges levelled against him.

He has been subjected to systematic torture, humiliation and degradation, deprived not just of his liberty, but of all rights normally afforded to those in custody yet to be proven guilty of any crime.

The time has surely come for a judge-led inquiry to find out the true extent of Britain’s role in the barbaric treatment of Mr Aamer.

Yesterday, the Daily Mail reported on the growing pressure on David Cameron from nine human rights groups for just such an inquiry into the CIA’s torture of prisoners, including Mr Aamer.

No human being should be subjected to such monstrous and prolonged treatment — 13 years, with no evidence produced to suggest a crime!

Nine human rights charities called for David Cameron to order a judge-led inquiry into the CIA's torture of prisoners

It is little wonder that one recent medical report stated Mr Aamer is now suffering from a host of serious health problems, including failing eyesight, kidney damage and depression.

This is, after all, a man who has been incarcerated for so long without trial that he has never even seen his youngest child, a 12-year-old son.

His experience is a scandalous affront to justice, making a complete mockery of respect for the law and due legal process.

Even cold-blooded murderers rarely serve as lengthy a sentence as Mr Aamer has had to endure, and, if they do, they will at least have been convicted in a court by a jury of their peers.

I have a deep personal involvement in the campaign to release Mr Aamer, ever since his case was brought to my attention by the renowned defence advocate Clive Stafford Smith.

With a spirit of selfless determination, Clive runs the organisation Reprieve, which campaigns for the rights, among many others, of British prisoners held overseas. Appalled by Mr Aamer’s plight, Clive had contacted him and lent him his support.

That is how I became involved. In one letter to Clive from Guantanamo, Mr Aamer began with the opening lyrics of one of my songs, Hey You, from the 1979 Pink Floyd album The Wall. Mr Aamer said the lyrics captured his experience in Guantanamo. These lyrics run:

‘Hey you! Out there in the cold

Getting lonely, getting old. Can you feel me

Hey you! Standing in the aisles

With itchy feet and fading smiles. Can you feel me

Hey you! Don’t help them to bury the light

Don’t give in without a fight.’

Clive was able to pass Mr Aamer’s letter on to me, and I was profoundly touched that Hey You had had such a resonance with him. Other parts of his letter reinforced how much this man was suffering. He explained that for most of the time, he had to stay in his tiny cell and was denied access to a computer, books, journals or even stationery.

He was occasionally allowed to write a letter, but even this was difficult because the pens provided by the guards were wobbly and soft, like a ballpoint with the plastic outer casing removed.

Apparently, this was a security precaution to stop the detainees attacking their guards — an obviously ridiculous measure, given that the guards outnumbered the prisoners ten to one and were armed with M16 rifles.

On a more uplifting note, in his letter Mr Aamer paid tribute to an American Christian pastor who had been in touch with him and had spoken of his work to build an understanding between Christianity and Islam.

Aamer has been subjected to systematic torture, humiliation and degradation at Guantanamo Bay (pictured)

This highlighted Shaker’s attachment to the idea of understanding between peoples and faiths, to the idea of reconciliation and peace, and his fundamental opposition to extremism.

But then, his entire story seemed to undermine the American claims that he was a dangerous extremist embedded with Al-Qaeda and bent on the destruction of Western civilisation.

Born in Saudi Arabia and trained as a nurse, he came to Britain in the mid-1990s, married a British woman and started a family.

In 2001, he moved with his family to Afghanistan, where he began work for a humanitarian charity. This fact is disputed by the Americans, who claim he became an Al-Qaeda fighter.

Really? Where is the evidence?

Shaker has never been allowed to defend himself in a court of law. In effect, he has been held purely on the whim of the U.S. authorities.

This abuse of power exhibits all the hallmarks of despotism. Either we believe in freedom to live under the law, including the law of Habeas Corpus, or we don’t. Either we, the so‑called enlightened West, are law-abiding or we are a tyranny.

Aamer was sent to Guantanamo (pictured) after he was seized by the U.S. military in Afghanistan in November 2001

Strangely, the U.S. government, the ‘tyranny’ that guards the rest of us from Shaker Aamer, now appears all the more culpable with the extraordinary news that the British Government has repeatedly called upon them to release him.

The failure to heed this request must raise suspicions that American and British intelligence are worried that, if Mr Aamer is set free, he might reveal the shocking complicity of British intelligence in the savage interrogation of prisoners at Guantanamo, and at secret rendition sites elsewhere in the world.

Last month, I attended a gathering in Parliament Square in support of a movement to free Shaker Aamer. Among the others present was the campaigning journalist Andy Worthington. Andy, to his eternal credit, has devoted much of his recent working life to exposing the horrors of Guantanamo.

I was proud to be there, standing as I did alongside other Brits who still care about the law, about standards, about justice, about fair play.

Thanks to the recent Senate report into CIA torture, the public mood has changed, maybe even dramatically, in the past few days.

It is possible people are coming to see that justice is important and that the British legal principles dating back to Magna Carta in 1215 enshrine the rights of the individual and are to be defended at all costs.