In the mid-1980s it was clear what the PDs were. With distinctive positions on the economy, the liberal agenda and the North, articulated by politicians of substance, the party filled not so much a niche as a medium-sized hole. That space is gone, taken over by the other parties as PD positions quickly became mainstream.

The PDs cling to relevance through participation in Government, but their long-term future depends on an ability to recapture the distinctiveness that surrounded them when they were founded.

The task was made even more difficult by the dragged-out inconclusive negotiations with Mr Michael McDowell. Plans to launch a new identity were put on hold - if he returned, Mr McDowell was to have a key role in policy, so they postponed decisions on detailed policy positions until the McDowell issue was resolved. But it hasn't been resolved. Mr McDowell hasn't rejoined but neither has he gone away. Party chairman Mr John Minihan says "never say never" but declined to say yesterday whether he has had any recent discussions with Mr McDowell.

The party does not now have the clear policy platform it hoped to launch this weekend, but it will outline a general shift of emphasis to social issues rather than just economic ones. In the last two months the party has conducted market research, hired consultants and set up an internal working group to refine its identity.

"Prosperity with a purpose" is the slogan for this year's conference, and if you think it sounds like the title of a bishops' pastoral, that's because it is. Last year the bishops produced one with just this title ("It's a complete coincidence," says Mr Minihan).

This weekend the party will indeed try to position itself as a party of tax cuts and social concern, a luxury available at times of record budget surpluses. But there is no shortage of tax cutters and socially concerned in the political market right now. The PDs will struggle to define themselves as a distinctive national movement on this policy position alone.

Mr Minihan admits they have a problem. "That gap in the market has moved, and we have to move on as well," he says.

How they must miss that gap in the market that gave them their crystal-clear identity of the mid-1980s. Then, half-way through the Fine Gael/Labour coalition, it was accepted that the economy was in danger of going down the tubes. Plane and boatloads of young well-educated people were leaving for the United States, Britain and elsewhere.

The national debt kept rising, contained only by rising taxes. There was talk that the Irish economy was such a basket case internationally that the International Monetary Fund might be called in - an outcome usually reserved for chronically failing Third World economies.

Into this morass arrived Mr Des O'Malley, a senior and experienced political figure whose confrontations and ultimate break with Mr Charles Haughey's Fianna Fail turned him into an anti-establishment figure. He said he had a formula, and together with Ms Harney, another figure of substance, he set out to form a new party proposing drastic spending reductions and commensurate tax cuts.

With this, along with policies on two other issues - Northern Ireland and the liberal agenda - the party struck a chord in the electorate.

On the North, both Mr O'Malley and Ms Harney were identified as opposed to traditional Fianna Fail nationalism, talking instead the language of pluralism and consent. On the liberal agenda, Dr Garret FitzGerald had placed these issues at the centre of political debate through the announcement of his "Constitutional Crusade". But while he had set out the agenda, nothing had yet been delivered.

His own government was undermined in this area in its capitulation to the anti-abortion lobby's demands for an abortion referendum, held in 1983.