THE SNP has enjoyed a triumph; Labour has been humiliated. The consequences are truly historic. For the first time in our history, the government of part of the United Kingdom will be led by a nationalist party committed to the fragmentation of the British Isles.

Of course, it would be possible for the three unionist parties to join forces and deny Alex Salmond the office of first minister. Together, they control 79 seats to the SNP’s 47. Such a coalition would represent the majority of Scottish voters and would deny the nationalists power.

It is an option, but it would be a mistake. The assumption of our political system has always been that the largest party has the first right to form an administration and only if it fails, or is subsequently defeated in a vote of confidence, should other parties have the opportunity to combine.

The SNP has won the most seats and, incidentally, most votes. To deny them the prize would cause resentment among its supporters and be a gross overreaction to a political earthquake that needs to be accommodated rather than ignored.

I might have taken a different view if I thought the SNP could be effective in using its power to destroy the Union. The reality is, that, as the largest minority party, it does not have a mandate either for independence or a referendum. Furthermore, any attempt by this minority administration to foment conflict with government in London by demanding oil revenues, or other polemical initiatives, can easily be blocked in the Scottish parliament.

The main danger is not the destruction of the United Kingdom but that it will be difficult to avoid years of constitutional instability if the SNP tries to exploit its new power to advance its separatist aspirations. That instability would be a real turn-off for investors.

If Salmond and his colleagues have Scotland’s best interests at heart, they should recognise that now, and for the foreseeable future, there is no desire to end the Union among the majority of Scots.

They should not ape the Quebec nationalists who condemned Canada to years of confusion and instability in their unsuccessful attempt to destroy the country. The party has now slumped to third place and has been rejected by its own people. The Catalan nationalists are a better model. They put separatism on the back burner and concentrated on providing good government for Catalonia within Spain.

But there is a responsibility on London and on Gordon Brown. Like it or not, the Scottish electorate has chosen the SNP. As democrats, Labour and the Conservatives must respect that and try to work constructively with an SNP administration.

Brown should take comfort from a historic parallel. In 1924 Ramsay MacDonald was allowed by the Conservatives and the Liberals to form, as a minority government, the first Labour cabinet. It was a comparable seismic shift in political history. It helped Labour reject its radical fringe and join the mainstream, but it led to them being overwhelmingly rejected by the electorate at the next general election. That, at least, might cheer up Brown.

Sir Malcolm Rifkind is a former Conservative foreign secretary and MP for Edinburgh Pentlands. He now represents Kensington and Chelsea.

Times Recommends

• Charles blazes trail as sun king
• Thalidomiders win payout 50 years on
• Libel gag on talk of 'medical hurricane'