The security services of Bahrain - a close Gulf ally of the UK - are alleged to have violently repressed dissident voices. A Briton commanded these forces. So why no prosecution?
Unrest marred Bahrain's recent past
With Britain a key player in the war with Iraq, what are the chances of a prosecution being launched in the UK which would cause severe embarrassment to one of our staunch allies in the Gulf, Bahrain?
This is not a hypothetical discussion topic, but a dilemma which arises from a little-noticed investigation being conducted by Scotland Yard.
In 2000, serious allegations of torture against a British citizen, Colonel Ian Henderson, were passed to detectives from the Yard.
Colonel Henderson, who is in his mid-seventies, has had an interesting career. In the 1950s, as a colonial police officer, he helped stamp out the Mau Mau insurgency in Kenya.
When Kenya gained its independence, he was dispatched to Bahrain - then a British protectorate - where he became head of state security for some 30 years.
Pro-democracy unrest was ruthlessly suppressed in Bahrain and allegations of brutality were made against both Colonel Henderson and his deputy, Adel Felaifel.
King Sheikh Hamad Bin-Isa Al-Khalifah is supreme authority
His family, from a Sunni Muslim tribe, has ruled since 1783
Bahrain gained independence from the UK in 1971
National Assembly dissolved in 1975, provoking Shia Muslim majority into years of unrest
In 2001, Bahrainis backed plan to turn their state from emirate to constitutional monarchy
An elected parliament and independent judiciary should be in place by 2004
Bahrain is an important military ally of the US and UK
According to organisations such as Human Rights Watch and Amnesty, the methods used to cow anti-government activists included beatings, sexual abuse and the ransacking of whole villages.
The fact that Colonel Henderson owns a property on the edge of Dartmoor puts him within the jurisdiction of the British courts and explains why Scotland Yard opened a file on him.
No formal details have been disclosed about this inquiry, although detectives are believed to have travelled to a number of European countries to interview potential witnesses.
At first, organisations which campaign against the use of torture, like Redress, were delighted at the possibility of justice for the many Bahraini victims of the regime.
Now, though, after nearly three years, questions are being asked about how serious this inquiry is and whether, even if the evidence is strong enough, the political will exists to prosecute.
Carla Ferstman, of Redress, says: "As far as we know, the police have not been to Bahrain - presumably because they would not be welcome there - and they have not questioned Colonel Henderson. Given the length of this inquiry, this may be thought surprising."
The vice-chair of the parliamentary Human Rights Group, Lord Avebury, goes further. "This is by far the strongest UK torture case we have seen, and yet the police investigation seems extraordinarily leaden-paced.
"We are completely in the dark about what the Yard has been doing. But if we discovered that they had been given a nod and a wink not to investigate too thoroughly to avoid embarrassing Bahrain, there would be a hell of a row."
In response to inquiries, a Yard spokesman would say only that "a report was sent to the Crown Prosecution Service in August 2001 but no formal decision has been taken on charges."
In a letter to Lord Avebury, the Attorney-General - who would have to approve any prosecution - said he was "serious about the UK's commitment to the UN Convention Against Torture".
As it happens, Bahrain is also a signatory to the convention - although in July 2002, the king showed his commitment to it in rather an odd way by issuing an amnesty to public servants who had committed acts of torture.
Australia, another signatory, had an opportunity to detain Adel Felaifel last year, when he visited Brisbane. But a similarly lethargic approach allowed him to leave the jurisdiction and return to Bahrain.
Lord Avebury said that when he visited the Gulf state in early January, victims of the state security police were "lining up" to show him the marks of their torture and many would welcome the chance to testify in an English court.
The chances of that happening do not look high. As for Ian Henderson, he denies the allegations of torture.