An investigation by the UK parliament has shown the full extent of British collusion with the US in the torture and extraordinary rendition of terror suspects after the 9/11 attacks, and throughout the military campaigns in Afghanistan and Iraq.

More than 15 years after the event, and following interviews with hundreds of intelligence personnel, the two reports detail in full the rights violations and inhumane treatment inflicted on prisoners under the justification of the war on terror.

Britain is a signatory of numerous agreements that outlaw such treatment, including the International Covenant on Civil and Political Rights, the European Convention on Human Rights, the UN Convention against Torture, and the 1949 Geneva Convention. In this light, the statistics make grim reading.

13 personnel personally witnesses cases of abuse. 25 were told of mistreatment by others who saw it. 128 were informed by foreign liaison services. 232 continued to cooperate with governments, despite being aware torture was used. There were 198 cases of UK personnel who knew they were receiving intelligence from tortured detainees.

There were 3 cases when funding was made towards rendition. 22 cases when MI5 or MI6 provided information for rendition. And 23 cases when no effort was made to prevent rendition.

19 allegations were made against specific UK personnel relating to abuse, including assault with a baseball bat. None of these resulted in criminal or civil prosecution.

Before the report's publication details were leaked to the press, with allegations the US tried to censor it. The chairman of the committee responsible for preparing the report, Dominic Grieve, said this was done to "draw the sting"  from the findings.

Beyond the figures the report's conclusions shed light both on the techniques used during torture, and the reasons why British intelligence felt compelled to cooperate in them.

Practices witnessed included sleep deprivation, starvation, stress positions, transport in coffin-sized crates, white noise, strobe lighting, extreme temperatures, use of menstrual blood, showing traumatic images, and placing a 30 pound weight around a suspect's neck. These techniques were described as "scientific progress".

UN groups, human rights NGOs and the Red Cross had highlighted cases of abuse at the time. However the report concludes this was not official government policy. These were seen as isolated abuses, rather than a systematic pattern of behaviour. The report adds it took time for the authorities to "join the dots" to understand the full scale of what was taking place.

One question was the extent to which British authorities knew of flights when terror suspects were taken to so-called "black sites" around the world, where they could be held seemingly above international law. The implication was that the intelligence services were "outsourcing action they knew they were not allowed to undertake themselves".

Although the report finds no rendition flights took place over UK territory, there were 2 reported cases when the British Overseas territory of Diego Garcia in the Indian Ocean was used, but with no evidence that suspects were held there. This was qualified with the comment that records on the island were "woefully inadequate".

The UK relies on an annual statement of assurance from the US to confirm their territories are not used for abuse of detainees. Though the committee preparing the report notes that since the Trump administration has a different view on detention to the Obama one, these statements cannot be relied upon, and does not guarantee that abuse might not take place in future.

Beyond the cases of abuse themselves, the report gives a revealing sidelight on the so called "special relationship" between Britain and the US, which allowed such close collaboration on rendition to take place.

The UK intelligence services place strong importance on information sharing with the US, "a democratic state with a broadly similar world view to ours". And cooperation was particularly necessary after 9/11 "in case they lost access to intelligence which could prevent an attack on the UK".

Nevertheless, it is clear from briefing meetings that the US would adopt a very strong approach to its national security. "The US response... will be typically American" read a note between the head of MI5 and the prime minister's policy adviser. Even though these agencies "clearly showed" their intent, the findings suggest this was "not taken seriously".

The US "would not stop until the enemies were all dealt with", "the gloves were off". The US agencies, a similar briefing paper notes, were "authorised" to "arrest targets anywhere, including in the UK and Europe".

The report considers the charge the UK "deliberately turned a blind eye" to more extreme activities in order "not to damage the relationship". It quotes senior members of the intelligence service who had "an unconditional reflex to support the US", and that such a response "came from the political centre" and was "inevitable".

The conclusion is that the UK did not want to appear a "poor relation" to the US, and was "uncomfortable at the prospect of complaining to its host". Although the report notes US actions were clearly "inexcusable", they were nevertheless "tolerated", out of a wish "not to upset US counterparts".

The report admits the UK was very much "a junior partner" in the arrangement and it had "limited influence" to affect how the war on terror was waged, and how suspects were treated.

Britain, it seems, is prepared to go a long way ethically to stretch its principles to keep some special relationship. It is clear the UK was in no position to stop the US intelligence agencies once their goals and methods were decided. But a refusal to take part could have cost the UK valuable information to protect its own security. A moral dilemma certainly. But hardly one you might expect an ally to put you in.