By the evening of 11th September 2001, Britain’s approach to the so-called ‘War on Terror’ had been set.
"We therefore here in Britain stand shoulder to shoulder with our American friends," said Prime Minister Tony Blair a few hours after the Twin Towers were struck.
But how close did Britain stand with its American partners when it came to the murkiest tactics of that chaotic era?
Thanks to a report published by the US Senate last year, we now know how brutal some of Washington’s detention programmes were.
American agents threatened violence against inmates’ families; meals were "‘pureed’ and rectally infused". Barack Obama admitted that some of the CIA’s methods were "contrary to our values". Many thought that to be an understatement.
Now, in his first television interview, the last British detainee in Guantanamo has drawn further links between the actions of the US and the UK.
Shaker Aamer claims that British intelligence agents were aware of his mistreatment by the Americans. He says one was present at the time an ‘enhanced interrogation technique’ was carried out.
Mr Aamer describes torture behind the razor wire at Bagram and Guantanamo - and alleges British complicity in American barbarity.
Guidance to intelligence agents makes the expectations of the British government clear.
In the most recent set of rules, staff at the spy agencies were told:
A 2013 inquiry by retired judge Peter Gibson found evidence that Britain might have been inappropriately involved in the ill-treatment of terror suspects, though not directly.
But after reviewing 20,000 secret documents, Mr Gibson offered no firm conclusions, just questions - 27 of them - about what the British knew about the actions of the Americans.
In the slow search for answers, his 119-page document included very few.
And almost fourteen years after Shaker Aamer’s detention, the allegations that he and other inmates have consistently made have been neither proven nor put to bed.
Today, there have been blanket responses from official sources.
A government spokesman said: "We do not participate in (torture), solicit, encourage or condone it for any purpose".
Jack Straw, the former Foreign Secretary, said: "I made it clear that the British government never condoned, nor was complicit, in the torture or ill-treatment of detainees, wherever they were held."
Further investigation is needed, and the parliamentary Intelligence and Security Committee is investigating claims that Britain was complicit in rendition and torture at Guantanamo Bay.
It is unclear when their findings will be revealed.
Until that moment, and perhaps beyond it, our spy agencies will face claims that their approach to terror suspects after 9/11 marked a departure from British principles.