The campaign to secure the release of the last British resident being held in Guantanamo Bay gained crucial momentum this week following a Parliamentary debate.

Shaker Aamer, whose wife and four children live in Battersea, has been in the Cuban detention centre without charge or trial for the last 11 years since he was captured in Afghanistan in 2002.

But on Wednesday, Battersea MP Jane Ellison opened the backbench debate, which was held at Westminster Hall and attended by Foreign Minister Alistair Burt, and a cross-party selection of MPs.

The debate itself was triggered when an e-petition, launched by his father-in-law, demanding the release of Mr Aamer reached 100,000 signatures.

Mr Aamer, who is currently 78 days into a hunger strike, has never met his youngest son, Faris, who was born the day he was transferred to Guantanamo.

He has also allegedly been tortured, starved and put into solitary confinement for 360 consecutive days.

During her speech, Ms Ellison described her constituent's detention as a "stain on democracy".

She said: "After 11 years, it is clear that the US does not have sufficient evidence against Shaker Aamer to bring charges, because if it did, it surely would have done so by now, as it has for many other detainees.

"We are left, therefore, with the fundamental questions: Why is Shaker Aamer still being held, and what are the conditions under which he may return to the UK?

"I put those questions directly to Brigadier General Mark Martins, chief prosecutor of the US office of military commissions in Guantanamo, when he came to the House of Commons last September, and to Leon Panetta, the outgoing US Secretary of Defence, when he visited the House in January.

"The official reason they both gave for Mr Aamer’s continued detention was that he was being held under 'the law of war, intended to prevent his return to the battlefield for the duration of hostilities in which he was previously engaged'.

"We are here today discussing a political problem, but behind the politics and the diplomacy there is a family tragedy.

"For many decades, the west criticised the gulags of the Soviet era, yet we seem to have replicated them."

In 2007, Mr Aamer was cleared for release to the UK but then, after the goalposts were moved without explantion, his lawyers were told he was only cleared for transfer to Saudi Arabia.

But two years later mysteriously the Saudi transfer was cancelled and he has remained imprisoned ever since.

Ms Ellison also referred to a Mail On Sunday article, written by David Rose, which suggested Mr Aamer may have been present during the torture of another detainee who, allegedly, later gave false information that was used to justify the invasion of Iraq.

Clive Stafford Smith, from legal charity Reprieve, described his client's detainment as " deeply suspicious".

He said: "Given that he could appear as a witness against the perpetrators of some the UK's dirtiest secrets over their role in the 'war on terror', it is far better for the intelligence services if he is sent away to another prison in Saudi Arabia."

Mr Burt, addressing the debate, said: "It is the long-standing policy of the Government that we should seek the release and return of those UK nationals and former legal residents who have been held at Guantanamo Bay.

"It is necessary for the Government to keep the details of diplomatic discussions with the United States administration confidential.

"A breach of its confidentiality in relation to it would damage the efforts that we are continuing to undertake in relation to Mr Aamer’s release."

Tooting MP Sadiq Khan, who was prevented from speaking at the debate because he is a frontbencher, has also campaigned tirelessly on for Mr Aamer's release.

He said: "I hope that today’s debate puts Shaker Aamer’s continued detainment securely on the Government’s agenda and forces them to be more aggressive in bringing him back to the UK.

"I was disappointed that the Minister could not explain why the US Government had held Shaker in Guantanamo for 11 years without charge, or why he is not being transferred or released to the UK.

"There can be no justification for him to be held for such a long time without charge. I will continue to campaign for Shaker Aamer’s release for as long as it takes."

The views of MPs who spoke at the debate:

Yasmin Qureshi, Labour MP for Bolton South East, said: "It has been suggested, certainly by his lawyer, that one reason Shaker Aamer has not been released is that he has stood up for his rights in prison.

"He has not seen his children or wife; in fact, one of his sons was born soon after he was detained and he has not even seen him.

"His detention is a blot on the reputation of America for upholding freedom and rights."

Caroline Lucas, MP for Brighton Pavilion, said: "Of the 14 people released to Britain (from Guantanamo), nine nationals and five residents, none has any involvement in extremism.

"By contrast, in Saudi Arabia, which has a vaunted rehabilitation programme, a larger number have committed subsequent acts.

"That is what leads us to the uncomfortable conclusion that the only possible reason for sending Shaker to Saudi Arabia is to stop him from speaking out about his abuse - abuse in which the UK authorities have been complicit."

John McDonnell, MP for Hayes and Harlington, said: "My view is that the Foreign Secretary should be summoning the American ambassador now, to say that this Government have had enough.

"If that causes an international incident, I do not care any more. We are talking about someone whose life might be lost in the coming months.

"That is more significant than upsetting one of our supposed allies."

Jeremy Corbyn, MP for Islington North, said: "The treatment of Shaker Aamer is appalling by any standards.

"The stories he will be able to tell will frighten an awful lot of people, and they will show just how precious an independent legal system is and just how precious it is to be able to represent yourself and your case in court."

Kerry McCarthy, MP for Bristol East, said: "Although national security is, of course, a paramount concern for both the US and UK Governments, the continued existence of Guantanamo Bay is also a fundamental human rights issue, which, many have argued-indeed, it has been said by Members in Westminster Hall today - is more likely to have jeopardised than safeguarded American security."

Anas Sarwar, MP for Glasgow Central, said: "If it was the other way around-if the UK had detained a US resident-would we be getting the same response, and would we accept it?"