When informed that David Trimble had just beaten John Taylor, among others, to take over the Ulster Unionist Party leadership, a very senior Sinn Fein figure reportedly went white in the face. It was September 1995 and Trimble was then Drumcree David who had held hands in a victory walk with Ian Paisley after the Orange march was completed on the Garvaghy Road.

To republican leaders looking for a way out of the cul-de-sac of political violence it must have seemed a crushing blow. The old dictum that nobody ever lost support in Ulster unionism by moving to the right had apparently received another gloomy vindication.

But nothing is ever quite what it seems in Northern Ireland politics. The sash-wearing hardliner of the Drumcree parade was the same David Trimble who braved denunciations of biblical proportions from the Rev Ian Paisley and others when he finally agreed to support Senator George Mitchell for the chair of the Stormont talks less than a year later.

Trimble has made other giant political leaps since then, the biggest - until yesterday - being Good Friday 1998. Senior UUP sources claimed it was much more difficult this week for Sinn Fein but, if they really believed that, they did not understand the extent of the risk being taken by David Trimble.

On (almost) all sides there will be an eagerness to assist the UUP leader in any way possible between now and the expected meeting of the Ulster Unionist Council in the Ulster Hall, Belfast later this month. While nationalist sources shared this anxiety to help, they were concerned that nothing should be done to unsettle a republican camp that is already somewhat rattled by speculation that decommissioning is on the cards for January.

For instance, any serious pulling-back from the key recommendations in the Patten report on policing would cause problems, nationalist sources insist. The possibility of Drumcree being used as a bargaining counter has also been mentioned, and if that happened it could cause enormous difficulties.

The pace of events has increased dramatically. There is no time to lose, and there is also an appreciation that Mr Trimble cannot amble towards victory over his party dissidents: he must strike and strike quickly.

The IRA statement will be brief, almost cryptic, but it will unleash other developments in rapid succession. The latest speculation was that a plenary of the pro-agreement parties could be held as early as tonight, with Senator Mitchell issuing the final report of the review tomorrow.

Each day there must be something new, some positive development to maintain the momentum and focus interest on the parties which are trying to implement the Belfast Agreement rather than those who seek to wreck it.

The Ulster Unionist Council meeting is expected to take place on November 27th. Presuming that the unionist faithful have endorsed the package on offer, the Assembly is likely to be reconvened in short order to nominate ministers. The farce of July 15th seems unlikely to be repeated this time: there will instead be a serious air, one of high drama and expectation rather than gloom and disillusionment.

The position of Mr Seamus Mallon is exercising some very sophisticated political brains at the moment. Restoring him to the post of deputy first minister without bringing down the whole house of cards will take the dexterity of a trapeze artiste, the cunning of Machiavelli and the breezy self-confidence of a television talk-show host.

Why give the nay-sayers time to organise their forces? was the view in pro-agreement circles last night. The triggering of the d'Hondt mechanism for the appointment of ministers will be rapidly followed by the first meeting of the new executive: at last we will see that first photograph, presumably minus the two DUP ministers.

All this will be fine and dandy until we come to the real crunch in January. Gen de Chastelain will be expected to answer the question: has the IRA "done the business" at last? Speculation that decommissioning was on the cards has been described by usually reliable sources as a rather liberal interpretation of the deal on offer from republicans.

The climate in the republican movement is not conducive at present to such an action, although the UUP leadership, not to mention the British government, will be looking for "product" from the IRA. Reporters who make a prediction one way or the other will become targets in the game called "Shoot the messenger".

However, there is no explicit public statement anywhere which guarantees that guns will be disposed of at such an early stage. And there is a belief in republican circles that once the movement has gone finally and definitively political, the weaponry will have to be put beyond the reach of those who would continue the armed campaign, not to mention other, more venal elements which might want to use the guns for criminal activities.

THE happiest man at Castle Buildings yesterday was Mr John Hume. Battered but unbowed after recent serious health problems, the SDLP leader had a smile on his face as he read the UUP and Sinn Fein statements.

The tortuous and unpoetic yet strangely effective diplomatic and political code known as "Humespeak" was everywhere in the texts from the other two parties.

When Mr Gerry Adams speaks of "transforming the existing situation through constructive and dynamic political development" and Mr Trimble declares his party's fealty to "the principles of inclusivity, equality and mutual respect" you can understand why the Derryman is entitled to feel there is now no turning back.