A British prisoner on Death Row in the United States is about to become the focus of a ferocious dispute between London and Washington.
Tracy Housel is the first Briton due to be executed in America since Labour came to power in 1997 and may be killed by lethal injection as early as next month. The British reaction to the execution at this crucial time is being viewed by human rights groups as an indicator of whether Tony Blair will be prepared to speak out if British al-Qa'ida prisoners are sentenced to death.
To raise the execution to the top of the political agenda, lawyers campaigning for Housel, who is 43, have engaged the support of 121 MPs and hired Macaulay Hobsbawn Communications, the public relations company of which Sarah Macaulay, the wife of the Chancellor, Gordon Brown, used to be managing director.
If Mr Blair does not intervene personally with the authorities in Georgia, where Housel has spent 16 years on Death Row, he will be accused of sending out the message that it is acceptable to execute British subjects. But if he does intervene, the "special" relationship between the two countries forged in the campaign against terrorism could be severely dented.
Housel was sentenced to death in 1986 for the murder of Jeanne Drew, a hitch-hiker whom he beat to death in Gwinnett County, Georgia. No one disputes that he committed the crime but, during his trial, he was represented by a lawyer who failed to introduce medical evidence to demonstrate that the defendant was brain-damaged as a child and suffered from blackouts.
Lawyers also argue that the prosecution should not have been allowed to tell the jury of crimes that Housel was never charged with, or to give the impression that he had been found guilty of them. Since his incarceration, medical experts have proved that when he committed the murder, Housel was in the middle of a hypoglycaemia attack that would have rendered him unaccountable for, and unable to remember his actions.
The US Supreme Court is expected to rule on a final appeal for clemency on 25 February. If the court throws out the appeal, the State of Georgia must set an execution date within 20 days and kill within seven days of the date.
Andie Lambe, of Reprieve, which fights for the rights of people on Death Row, said: "The only thing that can save him if the Supreme Court throws out the appeal for clemency is the personal intervention of the Prime Minister. Without his intervention, the execution will definitely go ahead but, with it, there is a chance that the Georgia Governor and Pardons and Paroles Board might reconsider.
"The timing is vital, too, because of the British prisoners being held in Guantanamo Bay. Jack Straw [the Foreign Secretary] has made it clear he wants them to be tried in Britain, but if Mr Blair does not become personally involved in Tracy Housel's case, it will send the message that it is OK to execute Britons."
An early-day motion introduced to the Commons by the Labour MP Vera Baird, calling on the Prime Minister to intervene, has attracted 121 signatures from all parties. But all Mr Blair has said is that he will do all that is "reasonable" to help avert the execution.
The MP said: "There is no doubt at all that Tony Blair is very committed to opposition of the death penalty, but will he think it is 'reasonable' to pick up the phone and make this call? There is no doubt that Housel committed the crime, but he was clearly brain- damaged. That is undisputed."
She said that in Britain Housel would have been charged with manslaughter, and even in America today he would not have been charged with first-degree murder.
Campaigners, who include Amnesty International, argue that prime ministers from Canada, Germany, Thailand and, most recently, Mexico, have successfully intervened to stay executions. The last time a Briton, Nick Ingram, was executed in America, in 1995, also in Georgia, a Pardons and Paroles Board member told The Independent that an intervention from John Major, the Prime Minister at the time, might have made a difference.
The Foreign Office said: "Her Majesty's Government is opposed to the death penalty in all circumstances. We very much hope Mr Housel will not be executed and we have made the authorities in Georgia aware of that. Our consul general has already held meetings with the chairman of the Pardons and Paroles Board and the Governor."
Walter Ray, the chairman of the Board of Pardons and Paroles, was not available for comment yesterday. Kathy Browning, his spokeswoman, said: "There is a set procedure whereby the board will listen to representations on behalf of the inmate. They can have an audience in person, but we also take letters, e-mails or phone calls. The board can stay the execution for 90 days to review the evidence, grant clemency and commute the sentence to life, or deny clemency."
He added: "If your Prime Minister were to make representations, they would be considered. We don't rule anything in or anything out."