The secrecy surrounding the whereabouts or even the correct identities of the two prisoners in the centre of the High Court case is a legacy of the shadowy operations carried out by the SAS in the most violent period of the war in Iraq.

The two men were arrested during a little-publicised campaign in which British undercover soldiers fought alongside their American counterparts in cities like Baghdad, Fallujah and Ramadi.

The suspects, members of Pakistan-based Lashkar-e-Taiba, the Muslim fundamentalist group believed to be responsible for the Mumbai attacks, were picked up by the SAS, handed over to American custody and soon got lost among the hundreds of prisoners being taken during this period. There was no official concern expressed at the time.

The British government, however, has been extremely keen to keep the activities of the SAS, and their Navy equivalent, the SBS, in Baghdad under wraps. With the rising unpopularity of the war, London was anxious to maintain a distance from the perceived excesses of the US forces. There was a repeated mantra that things were much more amicable, in the British-controlled Shia south. Disclosing that UK troops were not only fighting in the Iraqi capital but taking part in some of the bloodiest incidents would have undermined this self-serving portrayal of British "moderation".

From the outset of the war the SAS was determined to be positioned in Baghdad, where the action was. Tony Blair was initially supportive in the hope that the force would at last turn up Saddam's WMD. But the British special forces soon realised the futility of pursuing the mythical chemical and biological weapons and rounding up ageing Ba'athist officials. They turned instead towards a charismatic American commander, Stanley McChrystal, who was going after the real enemy – al-Qa'ida and the Islamist jihadists.

From their base in the outskirts of Baghdad, christened the "Big Brother House", the SAS and SBS were enmeshed in a world of nightly raids, targeted seizure and killing of suspects.

The British special forces rescued Norman Kember, the Christian activist, kidnapped in Baghdad, but failed to find Margaret Hassan, another hostage. They are also said to have killed or captured around 4,000 insurgents. Very little is known of these operations to this day.