Answer: 'Twenty five years.' It is an old joke and not a very funny one given the number of people who have died in the interval.
That one of Northern Ireland's smallest political parties has quietly voted to wind itself up has gone almost unnoticed. No, not the United Kingdom Unionist Party, but Democratic Left. While members in the Republic will join the Irish Labour Party, members here can join as individuals but cannot organise.
Through from Sinn Fein to Official Sinn Fein, to Sinn Fein The Workers' Party to The Workers' Party to New Agenda and finally Democratic Left, a few notable individuals have kept the flame of radical non-sectarian republicanism flickering in Northern Ireland. Winding up must be a bitter blow.
While the party was never to have made the big time in Northern Ireland, a few individuals such as Paddy Joe McLean, Mary McMahon and Seamus Lynch have all been significant players in left-wing politics. Down the years they have been fearless in exposing the fascism of those pretenders to the mantle of true republicanism. They deserve our thanks.
DL here has been the victim of an inevitable coming together of the Left in the Republic. The combined Labour/ DL vote fell from over 22% to less than 13% in last year's Irish general election. Indeed, Proinsias de Rossa, DL's charismatic leader, only just scraped home in his north Dublin seat. When the Left musters less than one in six Dail seats, having two left-wing parties made little sense.
Because the Irish Labour Party is a sister party of the SDLP, the DL members in Northern Ireland were left stranded _ unable to organise for fear of competing with the SDLP. Intriguingly, the SDLP's chairman, Jonathan Stephenson, has mooted a possible future tie-up between the SDLP and the new Irish Labour Party. That has has gone down like a lead balloon with many SDLP members whose socialism is skin deep and secretly identify far more with Fianna Fail than Labour.
Ideologically, the merger has been facilitated by the Good Friday Agreement. While the old Labour Party could have been described as light green, DL was depicted by its critics as light orange; believing that trying to undo the partition settlement was always a distraction from the unity of the working- class. Notwithstanding very different histories and traditions, the settlement of the Northern Ireland question left few ideological differences between the two camps.
Indeed, DL's commitment not to involve the Republic in any Western defence alliance and Labour's opposition to legalised abortion are the only major bones of contention. Since Labour's bedrock of support is in rural Ireland _ where DL has no base _ around 90% of delegates in both parties have been able to endorse the deal.
The new party has set itself the goal of achieving the Republic's first left-led government. Given that Fine Gael routinely pulls in around a quarter of the popular vote, that will be no mean feat.
The new Labour Party is hoping that it will be the major beneficiary when the population becomes more aware of the flip side to the Celtic Tiger: the terminally poor, the homeless and the badly paid. The record is, however, that the two main Civil War parties have an uncanny ability to project themselves as capitalism's friends and foes at one and the same time.
The Republic is still a socially conservative society but even the supposedly Thatcherite Progressive Democrats are to the left of Tony Blair on economic issues. In particular, the trade unions are accorded a far more privileged position than in the UK. The new Irish Labour Party will find it difficult to break the two 'right-wing' parties' dominance.
Ironically, the big winner from the weekend's decision could well be Sinn Fein, who have an excellent opportunity to appear as the only truly radical party, particular to working-class Dubliners. Having spent a generation fighting Sinn Fein ideologically, that must be the final insult for DL in Northern Ireland.
But then, if life was fair there wouldn't be socialists in the first place.