The fact that both sides distrust not just each other but also the Government itself was illustrated last week when David Trimble publicly expressed his dislike of the Secretary of State for Northern Ireland, Mo Mowlam. Unionists have always had a problem coping with strong, independent women, and Mo's informal style has never been to their taste.
Mr Trimble might also have been indulging in what could be called transference, in that he himself is distrusted by a significant section of his own party. His distaste for Mo is genuine enough, but the attack might have been intended to deflect criticism from himself.
Some of the elder figures of his party have lived in a permanently disgruntled state ever since he was elected leader four years ago. When, at Easter last year, he shed his image as an unreconstructed hardliner and signed up to the Good Friday Agreement, he came to be regarded with the utmost suspicion by the traditionalists. Attacking Mo Mowlam was therefore perhaps a signal that he had not gone soft and was not placing too much trust in the Government.
His decision to bring Jeffrey Donaldson back into his negotiating team might have had a similar motivation. The ambitious young Lagan Valley MP walked out of the Good Friday negotiations at almost the last moment, declaring later that he would not be party to any fudge on decommissioning.
He has ever since remained in limbo, often critical of Mr Trimble, often warning of possible sell-outs, but never quite in open rebellion. His recall, which followed detailed conversations with his leader, seems to transmit the message that they are equally determined to adhere to the party line on decommissioning.
Mr Trimble is such an unpredictable figure, and a man who confides in so few colleagues, that he is probably the greatest enigma on the Northern Ireland political scene. Observers differ widely on his gameplan.
Some think he will hold out for his goal of prior, or at least virtually simultaneous, decommissioning; some think he might settle for what Mr Donaldson could again regard as a fudge; some think he intends to kick for touch and try to postpone everything till the autumn. Quite a few think he's not certain himself what he will do.
One thing that is certain, however, is that last week's release of the Brighton bomber, Patrick Magee, represented exquisitely bad timing, both for him and for those who hope a deal can be done.
When the Good Friday Agreement was first signed, its provisions for the release within two years of prisoners belonging to organisations maintaining a ceasefire was the biggest shock of all. It caused much political and personal pain, but 71 per cent of voters came to accept it, and in fact actually brought themselves to vote for it in the referendum on the agreement.
But a great many Unionists do not believe the republican movement is committed to democracy, and the sight of Patrick Magee walking free reawakened much of the old anger. His bomb had, after all, killed five people in his attempt to assassinate members of the Thatcher cabinet.
That was 15 years ago, but many Unionists do not believe the republican leopard has changed its spots. Although the agreement does not equate prisoner release with decommissioning, the cry went up that the IRA was getting maximum gain while giving nothing in return.
The declaration during the past week that the Real IRA is back in business was another blow to the thesis that republicans as a whole are moving into politics. It was another pointed reminder that the Good Friday Agreement cannot of itself deliver peace, for the violent extremes on both sides are still in existence.
The Real IRA's only contribution to Irish history has been to wipe out 29 people - Catholics, Protestants, foreigners, men, women, children - in the Omagh bomb. And across the divide a selection of small but dangerous loyalist groups remain active, tossing their primitive petrol-bombs and pipe-bombs into Catholic homes. In their sectarian spree of more than a hundred attacks over the past year, they have managed to kill a police officer and a Protestant grandmother.
None of this precludes a successful negotiation, but clearly none of it improves the political atmosphere. And nor do the various historical hangovers which in Belfast are not just the stuff of history but also the stuff of everyday politics. The past haunts Northern Ireland, intruding on the present and interfering with its future. When Tony Blair finally gets David Trimble and Gerry Adams round the same table, the room will hold not just the three of them but also many ghosts.
It is not just the anniversary of the Battle of the Boyne in 1690, which Protestants will celebrate in a few weeks' time. The past three decades have given rise to a whole new set of grievances, many of which remain live political issues. Republicans and nationalists tend to be particularly zealous in keeping these to the fore. The inquiry into the Bloody Sunday deaths of 1972 will not really get off the ground until the autumn, but it has already generated much dispute on the issues of whether the paratroopers involved should have anonymity.
The killing in 1989 of the solicitor Pat Finucane, and the allegations of some sort of security forces' collusion in his death, continue to dog the authorities. This is clearly a matter of continuing international concern, with 1,000 lawyers having earlier this year called for an independent inquiry into the incident. Last week's admission in court by a man charged with the murder that he was an RUC Special Branch informer has ensured that intense interest in the case will be maintained.
Although most of these historical legacies concern the behaviour of the security forces, republicans have also received a bad press over the disappeared, those people they murdered and secretly buried in the 1970s. The IRA, which has made such hay over alleged security forces' wrongdoings, has had little to say in mitigation for the decades of heartache it caused to numerous families. The burial sites it pointed out a month ago have yet to yield any bodies, leaving grieving relatives to come to terms with the fact that their loved ones might never get a decent funeral.
All these issues, and more, will run on, whether or not this week's negotiations succeed or fail. If failure is the outcome, few really believe Northern Ireland will be plunged back into full-scale war, but there would certainly be a dangerous and unproductive vacuum during the summer marching season.
These talks are being billed as the last chance, but in the event of failure the probability is that the autumn will see yet another attempt. That could be the very last chance, when failure would mean that much of the agreement would have to be written off. Unionists and nationalists would then rush to cherry-pick those sections of the agreement they favour, arguing that they should be salvaged even if the main structure should perish. The Belfast assembly is the major part of the proposed new political architecture, and Unionists will argue for its preservation, but it will probably be mothballed. David Trimble would probably not survive as leader of the Ulster Unionists.
What would in all probability survive, however, is the new bond between London and Dublin, for at governmental level Anglo-Irish relations are the best they have been for decades. If it is concluded that the Belfast parties cannot be brought to agree among themselves, then the two governments may turn to each other to run the place in partnership as best they can.
Success, on the other hand, would banish such dismal thoughts, for if the decommissioning problem can be solved then a whole new vista of progress is possible - not guaranteed, but possible.
A new 10-man coalition executive would almost immediately spring into being, including Ulster Unionists and Sinn Fein members. Executive members would even, amazingly enough, include two of Ian Paisley's men, though he has specified that while they would accept ministerial office they would not sit down with Sinn Fein.
This executive would run Northern Ireland, with institutionalised links to Dublin; then policing would be reformed and anti-terrorist laws changed; an equality agenda would be introduced; then attempts would be made to demilitarise the streets and create a new society.
This would be social and political engineering on the grand scale, an attempt to make a fresh start by the creation of a new politics in which former deadly enemies can work side by side. But first next week's negotiations have to succeed, have to rescue the process from running into the sand, and have to provide a basis from which the exhilarating new enterprise can be launched. The hand of history will be on the shoulders of all those involved.
David McKittrick was last week named Feature Writer of the Year in the BT media awards.
Good Friday Agreement signed. Two Catholic men killed by loyalists.
Agreement endorsed in referendums north and south.
Elections to new NI assembly.
Drumcree marching stand-off in Portadown. Protests subside after three children die in firebomb attack on house.
Real IRA Bomb in Omagh, Co Tyrone, kills 29 people. British and Irish governments pass strong new anti-terrorist laws. Ceasefires declared by Real IRA, INLA and LVF.
Unionist leader David Trimble meets Sinn Fein president Gerry Adams for the first time.
David Trimble and John Hume collect Nobel peace prize. LVF hands in some weapons for decommissioning.
One-time "supergrass" and IRA critic Eamon Collins beaten and stabbed to death in Newry, Co Down, by unknown republicans.
Original date for power to be transferred from London to new institution in Belfast. Paratrooper Lee Clegg acquitted in a retrial of the murder of Belfast teenager Karen Reilly. Lawyer Rosemary Nelson, a staunch critic of loyalist organisations, security forces and the RUC, is assassinated.
High Court in Belfast rejects Home Office attempt to block release of four high-profile IRA prisoners, including Brighton bomber Patrick Magee.
Sinn Fein and the IRA told by British and Irish governments that disarmament is necessary to secure entry into Northern Ireland's new government.
Stalemate at Stormont as Sinn Fein reject decommissioning of some arms as part of procedure of setting up Northern Ireland government.
Irish government reveals suspicions of involvement of security forces in murder of lawyer Pat Finucane.
Orange Order says it will scale down protests against this year's ban on Drumcree march.
IRA agrees to give back bodies of the "disappeared".
Ten people arrested in connection with Omagh bombing in cross-border operation.
Brighton bomber Patrick Magee released from prison amid fury from Unionists.Reuse content