It is four years now since then Foreign Secretary David Miliband confirmed (despite previous government denials) that two extraordinary rendition flights had stopped over at Diego Garcia, the British overseas territory, in 2002. Addressing the issue of whether the Government had deliberately misled the public over its knowledge of - or collaboration in - rendition, Miliband apologised and stated that “mistakes made in those two cases are not acceptable”.

The revelations about Diego Garcia were symptomatic of the slow, piecemeal uncovering of information about the UK’s potential role in the ill-treatment and torture of terror suspects after September 11, 2001. The hazy picture of what occurred has begun to be pieced together by the first-hand accounts of victims, investigations of journalists and human rights organisations and protracted litigation in the courts, despite the best efforts of the government to keep everything out of the public domain.

Other information which has come to light includes UK intelligence personnel being present during and participating in interrogations of detainees held unlawfully overseas in circumstances in which the UK knew or ought to have known that they had been or were at risk of being tortured; UK personnel providing information that led the USA and other countries to apprehend and detain individuals when the UK knew or ought to have known that they would be at risk of torture; UK personnel forwarding questions to be put to individuals detained by other countries in circumstances in which the UK knew or ought to have known that they had been or were at risk of being tortured; UK actors soliciting, receiving and using information extracted from people detained overseas in circumstances in which it knew or ought to have known that they were being, had been or would be tortured. See, for example, publications by Amnesty International and by Human Rights Watch.

These and other revelations led the Prime Minister, on 6 July 2010, to announce the creation of an inquiry into whether the UK government and its intelligence agencies were implicated in the improper treatment of detainees held by other countries in counter-terrorism operations in the aftermath of 9/11. The inquiry was always going to have a difficult task. The cynics would say that it was created because the information that had already emerged required a governmental response, and the easy response was to create an inquiry which would give the appearance of accountability, without actually or necessarily being fully accountable.

David Cameron rightly underscored what his predecessors had also emphasised – the abhorrence of torture in all its forms – and promised that the official inquiry, led by Sir Peter Gibson, a retired appellate judge and former intelligence commissioner, would get “to the bottom of what happened”.

Yet, the terms of the inquiry were such that it was unlikely that it would have been capable of arriving at the whole truth. As a result, many human rights groups and victims decided to boycott it. Their concerns were echoed by the UN Special Rapporteur on Torture, Juan Mendez, who noted that a flawed inquiry would only do more harm than good: "A less than open and transparent inquiry would only serve to cover up abuses and encourage recurrence,” he said.

Any inquiry into allegations of torture that aimed to fulfil the UK’s international human rights obligations should have been independent, impartial, thorough and capable of leading to the identification and prosecution of persons responsible. It should also have provided for public scrutiny and victim participation. The inquiry was insufficiently robust on these points.

One of the most significant failings of the inquiry was that the Cabinet Secretary would have had the final say on what material was to be published, rather than an independent body or court. Certainly, the inquiry would need to safeguard confidential information vital to protect national security interests, yet the inquiry’s procedures gave the government, whose very actions were the subject of the inquiry, the role of sole arbiter of what was, or was not, a matter that could be shielded from the public. Other countries have given the courts the role of balancing the needs for national security confidentiality with a process accepted as independent and thorough and therefore likely to deliver an accurate outcome.

Another key flaw was that the inquiry didn’t offer a real opportunity for survivors or their representatives to cross examine evidence from members of the security services, almost all of which would be given secretly. This would have denied the right to challenge the official version of events and get the full picture of how these incidents were allowed to happen and what role the government played.

In the end, it was not the opposition of human rights groups and victims who delivered the fatal blow to the inquiry, but last month's announcement by police that they would be launching a fresh investigation into charges that Britain had participated in the rendering of terror suspects to Libya, where they were tortured. Justice Secretary Kenneth Clark said on 18 January in the Commons that it was impossible for the inquiry to start under these circumstances, but promised that – one day – there would be a new judge-led inquiry into allegations which are doing damage to the UK's reputation.

While the current focus on criminal investigations is appropriate in light of the seriousness of the allegations, this should not detract from the government’s undertaking to hold a judge-led inquiry. Addressing complicity in torture must go further than rooting out a few “bad apples” through criminal investigations. It is important that the government’s anti-torture commitment is properly scrutinised and fully implemented. A new inquiry must therefore come sooner rather than later.

The government should seize the opportunity to proceed on a stronger and more independent and transparent footing. A future inquiry should be capable of determining the extent of any official complicity in torture and how it was possible for such complicity to take root. This would require the government to strike a better balance between protecting national security interests and restoring public confidence and accountability. Any inquiry should also establish clear and effective mechanisms to prevent recurrence. Only this would restore fully the government’s moral authority in the fight against torture in all its forms.