The picture of Ian Paisley's tonsil-revealing guffaw as he stood beside an ecstatic Martin McGuinness featured widely in newspapers' coverage of the return of devolved government on Tuesday.

Paisley's elation may have reflected his claim that the deal he signed off on with republicans is a much better one for Unionism than that negotiated by David Trimble.

There is a grain of truth in that belief.

Trimble let his commitment to the principles of the Belfast Agreement keep him in negotiations with Adams and McGuinness despite the IRA's long-fingering of decommissioning and the clear evidence of the Assembly elections of 2003 that a majority of the unionist electorate had parted company with his strategy.

But the DUP claim that it was their tougher line that brought the final jettisoning of arms is simply wrong.

It was the threat to Adams' election hopes North and South brought about by the Northern Bank robbery and the murder of Robert McCartney that forced the IRA into retirement.

It was perhaps symptomatic of our new political culture that neither Trimble nor Seamus Mallon was invited to the ceremony on Tuesday.

The DUP/Sinn Fein duopoly's lack of generosity of spirit was one indication that, despite the heavy indulgence of easy sentimentality on the day, what distinguishes both of these parties is a rather inflated sense of their own importance and an intolerance of opposition.

Both have a culture of leader-worship and internal authoritarianism.

A couple of days ago during its southern election campaign Sinn Fein, perhaps embarrassed by their President's less than impressive defence of their economic strategy during a radio interview, announced that their long-held commitment to raise the rate of corporation tax was being dropped without any evidence of internal party discussion or debate.

The 'Doc's' views on taxation policy have yet to be expounded but in an interview with Frank Millar of the Irish Times he declared that he had no problem with supporting the demand for a lowering of corporation tax in the North to the same level as the Republic's. Millar expressed some amazement as did the nationalist-inclined Guardian that a unionist leader had signed up for a policy that is central to the republican project of the economic unification of the island.

Now DUPers unblushingly join in with Sinn Fein's denunciations of the lack of investment in infrastructure under Direct Rule when even six months ago they would have been vociferously pointing out the massive damage to infrastructure and diversion of resources caused by the IRA campaign.

But Paisley's real enemy throughout his almost 60 year political career has not been nationalism, republicanism or the IRA but the Ulster Unionist Party. His present acceptance of the structures of the 1998 Agreement, which he so bitterly denounced, is clear evidence of this. Being top dog of unionism was what it was all about whatever the long-term implications for the Union.

Sinn Fein in government in the Republic is no worry to the 'Doc' and he claims to have asked Bertie Ahern why he wasn't prepared to go into coalition with them.

But a government in Dublin which included Sinn Fein or depended on their support, would contain a great potential to destabilise north ?south relations . A senior official in the Department of Foreign Affairs once said that republicanism was like a shark - it had to keep moving forward or it would die.

The large group of Shinners who were celebrating in Stormont post-ceremony were unlikely to be doing so because they believed that they had seen the end of 'push-over Unionism'.

? Henry Patterson is Professor of Politics at the University of Ulster. His new book Unionism and Orangeism in Northern Ireland Since 1945 is published this week.