Leading article: The way to shared government is now open

Finally, though, they realised that they had to agree to put away their guns. They should have done this in 1994, when they declared their first ceasefire, but they did not: at that point they simply downgraded from full-scale terrorism to lesser illegalities. After that, extreme loyalists became the main takers of life, but the IRA continued to kill, to "punish" alleged miscreants, to recruit and train, and to carry out robberies and other criminality.

All that was suddenly turned off at the end of July, when the IRA said it was calling off its campaign. Yesterday was the crucial follow-up to that: confirmation that the words had been followed by deeds.

Now comes the verification. Republicans have a strong sense of personal honour, but - paradoxically - the IRA has also felt free to tell lies. A recent obvious example was its denial that it carried out last year's Northern Bank robbery in Belfast.

This is why its behaviour must be subjected to the most meticulous probing; and it will be, by London, Dublin, Washington and the wider world. The scrutineers will also include Ian Paisley and his Democratic Unionist Party, which has been in control of Protestant politics since the last election.

Mr Paisley may or may not be up for a new power-sharing arrangement, but everyone knows there will be no new administration without Sinn Fein. Everyone also knows there will be no DUP-Sinn Fein pact unless Mr Paisley is completely convinced that the IRA has completely gone away. And he will not be prepared to make a leap of faith. It will probably be many months before his ancient, almost genetically suspicious mind reaches this conclusion.

This means that no instant political breakthrough is on the cards. Uncertainties remain, and many of them. The significance of yesterday's announcement, though, should not be underestimated. There is a real sense of new potential and new horizons for Northern Ireland. Shared government remains some distance away, but a route towards it now exists.

Above all, in a world fraught with so many dangers, including terrorism, the news that the IRA is going out of business should be an occasion for huge satisfaction and relief. It has been a nerve-racking peace process, with as many reverses as advances. But for those who stuck with it - who kept the faith - this is a moment to savour.