Was that it, then? Mr Tony Blair's "crackdown on terror" came with all the usual New Labour hype - and spectacularly failed to fulfil its promise.

It is a curious fact (not necessarily of itself a bad thing) that London has been seen to be struggling to catch up with the speed, clarity and ferocity of Dublin's response to the Omagh massacre. And while there was a general political welcome for the Prime Minister's announcement in Omagh yesterday, the immediate judgment must be that London's response still falls significantly short of that signalled by Mr Ahern last week.

As expected, Mr Blair confirmed the emergency recall of the British parliament. On Wednesday and Thursday of next week, MPs and members of the House of Lords will be asked to approve a Bill designed to secure convictions for membership of proscribed organisations on the evidence of a senior police officer of superintendent rank or above.

The Bill - amending the Prevention of Terrorism Act and the Emergency Provisions Act - will allow courts to draw an inference from the silence of a suspect during interrogation. It will also incorporate a new Home Office measure creating a new offence of conspiracy to commit a terrorist offence in a foreign country.

The Prime Minister said the proposed changes were of a "draconian and fundamental nature". And he will know that many Labour MPs, and not all of them on the "old" Left, will share that view. Their opposition will be rendered impotent by the scale of the bipartisan cross-party support for the new measures.

But even as they vote them into law, the MPs - Conservatives and unionists chief among them - will know that the result is not that foreshadowed last week by Dr Mo Mowlam.

The Secretary of State suggested the result of the concerted London/Dublin security initiative would be the toughest, most effective set of anti-terrorist laws ever known on the island of Ireland.

Given her known disposition, it seemed unlikely, even in the bitter, angry aftermath of Omagh, that this promise would be made good. The Secretary of State also struck many as a touch smug in suggesting that it was largely a matter of the Irish catching up on powers long-available to the British.

In the event, it is clear that the shortfall remains on the British side. The existing British provisions, for example, do not allow for the seizure of property, including land, which has been used for storing weapons or making bombs. This was a key element in last week's Irish Government package. But the most glaring difference is that the Republic retains the power to intern without trial, while there is no such provision in the United Kingdom.

The Taoiseach and other Ministers last week made it clear internment remains an option should the `Real IRA' and other dissident republicans seek to destroy the Belfast Agreement and thwart the freely expressed will of the peoples of the island.

At the same time the potency, indeed the very reality, of that threat from Dublin would appear seriously undermined by the apparent determination of the Blair government not to reclaim the internment power scrapped by Dr Mowlam earlier this year.

A Downing Street spokesman last night told The Irish Times the government had decided firmly against restoring the internment power to the statute book, adding that there had never really been any serious discussion of the option. The Prime Minister and Secretary of State took the view that internment had previously proved counter-productive - a view, he said, reinforced by security advice.

Mr Blair's resistance to reinstating the internment power (a move which would undoubtedly cause serious trouble inside the Labour Party) enables Mr William Hague, the Conservative leader, to observe that, even with the additional laws announced yesterday, Mr Blair is armed with significantly less power that the previous Conservative government had on the statute book.

More importantly, perhaps, Mr Blair (if he remains firm on this issue) has set the scene for a potentially damaging row with Mr David Trimble, Northern Ireland's First Minister.

It was noticeable that Mr Trimble last week spoke warmly of the Irish Government's immediate reaction to Omagh, and reserved his only critical public comments for the British. Crucially, too, sources close to the Ulster Unionist leader emphasised he had expressed the hope that the various legal refinements under consideration would have the intended effect - rather than the confidence that they would.

It is understood Mr Trimble is not, in fact, convinced that the new laws, designed to secure easier convictions for membership of proscribed organisations, will work, or prove "judge-proof". And neither Mr Blair nor Mr Ahern can be in any doubt that, in the final resort, Mr Trimble believes the Executive must be prepared to accept its responsibility to suspend the liberty of terrorist suspects in order to protect public safety.

Mr Trimble was plainly impressed by the depth and sincerity of the Taoiseach's response to Omagh, and his determination to "crush" those responsible. The Ulster Unionist leader understands, all too well, the logic which drove the nationalist agenda leading to the Belfast Agreement - and the attendant promise that, given approval North and South for a settlement on Northern Ireland, there could be no further tolerance zone for those committed to continuing terrorism in the name of the Irish people.

And he considers it a manifest absurdity that, at the very moment when an Irish Government is seemingly prepared to consider internment, the whole point, purpose and effectiveness of such a course of action would be diminished by the ability of the suspects to "slip the net" and escape to Northern Ireland, where they would face no such danger.

Right or wrong, it is clear that for as long as London lags behind the Irish in their anti-terrorist provisions unionists will remain unconvinced of their government's willingness to do "whatever is necessary" to defeat the on-going terrorist threat.

As they ponder the choices and risks they want Mr Trimble to take in the coming weeks and months, Mr Blair and Dr Mowlam must know the retention of unionist confidence has never been more crucial. They must also be aware that Mr Trimble is in no fit shape to take too many political defeats.