Shaker Aamer: A man on a mission to shut Guantanamo down, and make sure it never happens again

But the colour of his shirt tells you something very different.

You might be familiar with the image.

A big, bold man with a bushy beard and specs - grinning broadly and waving at the camera, as if he's just arrived on holiday.

But the colour of his shirt tells you something very different.

It is bright orange. It is the jumpsuit worn by the prisoners of Guantanamo Bay.

For 14 years, this is the picture the world has had of Shaker Aamer: The last Brit to be released from the notorious detention centre, which President Obama has described as 'a symbol around the world for an America that flouts the rule of law'.

For 14 years he has endured physical, mental and spiritual torture in detention: Not once charged with, or tried for, any crime.

For 14 years, the clamour and campaign for his release grew - at the same rate of the mounting injustice of his incarceration.

And then, one hot night this October, an American colonel cut the last plastic ties binding Shaker Aamer's wrists and let him mount the steps of the plane to fly home to Britain. He was so disorientated and elated, he hit his head on the plane door as he stepped inside.

To see him in the flesh, it's hard to take in how well he looks - how unbowed and how robust he appears after an unimaginable ordeal.

Immaculately dressed - pressed shirt and chinos, sturdy walking boots: the beard now traced through with silver, curling black hair tied back from a broad forehead - and an even broader smile.

Shaker Aamer has kept his smile, says Julie Etchingham Credit: ITV News

How had he smiled in that photo at Guantanamo Bay? It was because he knew it would be the photo his four children would see.

One of those children he only met for the first time this October - born after he was captured in Afghanistan and sold to the Americans.

And now after being silenced all these long years, Shaker Aamer is ready to speak out. For two and a half hours he unpacked his incredible story for our cameras.

Most movingly, he talked about the heartbreaking reunion with his family: how he mixed up the names of his kids because he was confused which one was which.

How bit by bit both they and he are adapting to effectively a new relationship. And how after years with artificial light and air conditioning, he is even finding it hard to breathe fresh air and to sleep in darkness.

In a quiet voice he also makes devastating allegations about his treatment at the hands of the Americans, particularly at the airbase in Bagram where he was first interrogated, and he alleges, tortured.

Shaker Aamer alleges he was tortured

He claims British agents were there as it happened - and at one point, addresses one of them on camera, in case he might be watching. It is chilling stuff.

And he lifts the lid too on the living hell of Guantanamo Bay - the beatings, the mind control and the hunger strikes.

Some guards used to blare out Bruce Springsteen's 'Born in the USA' when it was prayer time for the Muslim detainees. But he acknowledges, too, that some showed him kindness.

He also tells me why he travelled to Afghanistan two months before 9/11 on a false passport - and why he wanted to take his wife and family to live under the regime of the Taliban.

And he answers hard questions on why the Americans deemed him 'high risk'.

But what in the end is so extraordinary about Shaker Aamer is his own personal resilience and optimism, as he tries to rebuild his life.

He wants a public inquiry into the activities of the British intelligence services - but is not seeking prosecutions.

His one and only mission: To stop another Guantanamo from ever being conceived of or built again.

As he tells me with this hands spread wide: "This is bigger than just Shaker."