DENIS DONALDSON will be remembered as the British agent at the heart of the republican movement who nearly toppled the Northern Ireland peace process not once, but twice.

As Tony Blair and Bertie Ahern, his Irish counterpart, unveiled their final plan this week to restore the Province’s political structures, they must have reflected on the cruel irony that a man at the centre of the IRA spy-ring allegations which brought down Ulster’s power-sharing executive 2½ years ago could yet, in death, scupper the prospect of restoring those same institutions.

Mr Ahern is on record as calling the “Stormontgate” affair “as bizarre as it gets, for who would have thought that an informer in the pay of the British Government could turn out to be the instrument for the undoing of all that Mr Blair has worked so diligently for throughout his prime ministership?”

But was Mr Donaldson’s exposure, set in motion by the uncovering of an IRA intelligence-gathering operation inside the Northern Ireland Office, a matter of conspiracy or cock-up?

Like a torch beam in a dark forest, the Donaldson affair has briefly sent shafts of light into the blackest recesses of the “dirty war” that has been waged down the decades in Northern Ireland.

It is a complex, murky world in which there appear to be no clear answers and where the imperatives of political deal-making collide, sometimes with catastrophic results, with the brutal realities of intelligence-gathering.

The facts are few. Irish police have established how Mr Donaldson died but have no clear lead, although they suspect Republicans were responsible.

Mr Donaldson was hit by four blasts from a shotgun as he tried to keep his killer out of his primitive cottage in Co Donegal.

The assassin or an accomplice initially threw a stone that smashed a front window, presumably to draw him outside. Mr Donaldson had no intention of revealing himself. He tried to bolt the front door or to put his weight against it. The gunman fired the first two shotgun blasts through the door and as Mr Donaldson staggered back towards the rear room, the killer reloaded, leaving the spent cartridges on the ground, and entered the cottage.

There was no back door and the 56-year-old victim, trapped and wounded, put his right hand over his face in a vain attempt to shield himself. The third and fourth shots, one to the body and the other to the head, killed him.

The attacker apparently fled immediately, without ejecting the other cartridges, and escaped from the remote wooded district, possibly with the aid of an accomplice. Nobody saw or heard the shots and because the murder weapon was a shotgun there is no trail for forensic scientists to follow.

The suspects are legion. As an informer and a British agent, in the eyes of the IRA Mr Donaldson automatically sentenced himself to death. If the organisation’s ruling Army Council did not pass the sentence or approve the killing, because of its commitment last summer to ending its activities, that would still leave any number of its members, past or present, with the incentive to carry out an unsanctioned murder. The sad and brutal truth is that in republican circles there will be few tears shed.

A second possibility is that the IRA is showing early signs of fracturing into factions as it lapses into inactivity and that mavericks carried out the killing to make a point to the leadership, knowing that Mr Donaldson’s unpopularity would make it impossible to punish them.

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