Yesterday morning, the kidnappers delivered their ultimatum for Mr Bigley's life, repeating their demands that all female prisoners in Iraq be released

The torment suffered by Kenneth Bigley and his family is past imagining. The initial 48-hour deadline is long gone.The two Americans taken hostage with him, in a suburb of Baghdad regarded as relatively safe, have been executed by their captors in the most barbaric way, 24 hours apart. Yesterday morning, the kidnappers delivered their ultimatum for Mr Bigley's life, repeating their demands that all female prisoners in Iraq be released.

Suddenly a glimmer of hope appeared on the horizon: the Iraqi authorities stated that they would release one of the two scientists said by the US to be the only Iraqi women still in custody. The US embassy in Baghdad denied it. Members of Mr Bigley's family, who had earlier implored Tony Blair to intercede personally, made another videotaped appeal to the kidnappers to be broadcast on the Arab television station al-Jazeera. From one hour to the next, everything seemed to be negotiable - and nothing - in the cruellest possible way.

Over the past six days, Mr Bigley, in his makeshift blindfold, has been the human face that reflects back to us the sharpening battle for Iraq in all its ruthlessness and confusion. At its simplest, his plight is that of all foreign civilians in Iraq, especially those from the countries most closely associated with the occupation. But it also highlights the manifold questions which still have no answers.

First: the competing assertions and denials about prisoner releases yesterday demonstrated that one of the key disputes that was supposed to have been resolved with the handover of sovereignty to the interim Iraqi administration at the end of June has not, in fact, been settled. It is not at all clear who has power or jurisdiction over the prisoners still held in Iraq. If the Iraqis do not have authority to release these prisoners, if - as it appears - there are several classes of prisoners and the Iraqi authorities do not even know precisely who is being held in their jails and who is within their jurisdiction, their sovereignty is even more illusory than we feared.

Second: if there is any release of prisoners in coming days, including so-called "high-value" prisoners, it is just possible that this was already in progress and is unconnected to the demands of the hostage-takers. The impression created, however, will be quite the opposite. It will be that terrorism achieves results that cannot be achieved by more civilised means; that the authorities - US, British or Iraqi - bend before brutality, despite their fine words to the contrary. This would not augur well for any diminution in the present lawlessness in Iraq. Power, Iraqis might well conclude, proceeds if not from the barrel of a gun, then from the blade of a knife.

Third: all the governments concerned, our own included, are right in their public insistence that they will not deal with terrorists. In one way, the failure of the French government to obtain the release of its journalist hostages was helpful to the British in that it demonstrated the futility of even such elaborate diplomatic efforts. This does not mean, however, that the Government should not be extremely sensitive to the agonies of hostages' families.

Perhaps because expectations of a positive outcome were so low, once Zarqawi's group was identified as responsible, officials appear to have acquitted themselves better in Mr Bigley's case than sometimes before. That said, Mr Blair's showbiz style appearance with Richard Branson to launch Virgin's tilting train struck a very wrong note.

The kidnapping of a Briton by Zarqawi's group must have been among the scenarios that the Government had most feared. For in one way, Mr Bigley's family was right when it identified Mr Blair as culpable: the Prime Minister is the one who bears ultimately responsibility for Britain's current involvement in Iraq. That neither he, nor anyone else, can exert the slightest influence on the desperate situation he did much to precipitate is a measure of the impotence of all authority almost anywhere in Iraq.