THE ministers floating around the Whitehall Christmas press reception one evening this week were effusive in their praise of John Major's role in the Anglo-Irish peace accord, stressing it was his initiative and his alone. It may just be the cynicism of the press, but everyone took that to mean that if and when the initiative founders in a few weeks' time they want 10 Downing Street to take the blame and nobody else. John Major has already marked a significant change in thinking on the British constitution. The Union with Northern Ireland has traditionally been an article of faith of the Conservative and Unionist Party, as it was until recently called. John Major now describes Unionists' belief as a ''personal right'' - if Northern Ireland wants out of the Union he will not stand in its way. Amid a series of bombings and security scares this week, there is a growing feeling that the boldest step in 25years to end the violence of Northern Ireland may well not work. Everybody desperately hopes that they will succeed, of course, but the route to be marched is yet a long one. It is, for example, vital that the two governments in London and Dublin speak with one voice. Yet only four days after Albert Reynolds and John Major stood together in Downing Street to announce this new Joint Declaration, the Irish Prime Minister was hinting of a policy anathema to Britain - that there might be an amnesty for IRA prisoners if itsues for peace. Albert Reynolds made the biggest faux pas so far by suggesting that if a permanent ceasefire were to be agreed, the status of terrorist prisoners could become part of the talks which then might take place between Sinn Fein and British officials. The future of prisoners would undoubtedly be part of the first exploratory talks between the British Government and Sinn Fein, he said. There had been no mention of this at all in the seven-page declaration. British officials claimed he had ''gone rather beyond the agreement''. Albert Reynolds' statement shows the still large gap in understanding between London and Dublin. An amnesty would be much more difficult for the British Government than Dublin quite simply because the terrorist crimes have been carried out against British people on British territory. John Major has refused to discuss any early release for any of them. The apparent differences have enabled Sinn Fein president Gerry Adams to place an amnesty at the top of the peace agenda, driving the wedge between London and Dublin even deeper. Not that anybody expects an early response from Sinn Fein, the political wing of the IRA, to the peace initiative. It is emerging that the republican movement is riven with factions. Some sections want to talk peace while others see quite clearly that the Joint Declaration falls far short of their aim of seeing an end to British involvement in Northern Ireland. At the same time, Sinn Fein does not want to be seen to scupper the peace prospects too soon; there is a recognition that if the IRA opts to keep on bombing there will be an almighty clampdown, and the international opinion in parts of the world which has kept it in funds and weaponry may well be less sympathetic. But there are contradictions on the British side. London has always insisted that there are no political prisoners in Northern Ireland jails; that imprisoned terrorists have been treated just the same as any other criminal perpetrating such crimes. Nonetheless, terrorists do have a de facto special status within the prison system, even special areas for each terror group where they can still to a degree organise themselves. The IRA even calls its prisoners in the Maze-Long Kesh prison its fifth battalion. They regard themselves as entitled to release en masse once peace is achieved. Even this week, hundreds of republicans and loyalist terrorists, including vicious sectarian killers, were allowed home for Christmas. Virtually all those with 11 years served are eligible for the scheme and none has so far failed to return. It would be hard, if not impossible, for Sinn Fein and the IRA to sell a lasting peace to its grass roots without an amnesty for its ''veterans''. There are 1,550 men and women serving sentences for terror-related offences in Ulster prisons: 29 per cent are republicans, 22 per cent loyalists and the remainder are minor offenders or those with no discernible alignment because they have renounced violence. Ironically, it would be easier to free murderers serving life sentences early because that can be done at the discretion of the Home Secretary or Northern Ireland Secretary while there are set minimum terms for those charged with other crimes, such as conspiracy to cause explosions. Changing that would need legislation in Parliament, and uncomfortable debates for the Government. And, of course, an amnesty for republicans would also mean an amnesty for loyalist terrorists including some of the more evil killers like the Shankill butchers, a gang who tortured, murdered and mutilated 19 people in the late 70s. How would the republican community welcome their release? It also begs questions of how the police should respond now: what would be the point of chasing killers and pushing them through the costly judicial system if they will be freed soon? Supposing there is a ceasefire; its terms must be agreed well in advance by both London, Dublin and Sinn Fein. Would that involve immunity from prosecution from then on? How would disarmament be handled? Would there need to be guarantees on the handing over of weapons to a neutral arms dump with assurances that they would not be forensically tested? How would that lie with the conscience of the Royal Ulster Constabulary? There are still many obstacles to peace, perhaps 1,550 of them.