Analysis: At Westminster they couldn�t remember an occasion like it � a sitting of the Commons having to be suspended because a minister had failed to arrive in the chamber.

At Westminster they couldn't remember an occasion like it - a sitting of the Commons having to be suspended because a minister had failed to arrive in the chamber.

Douglas Alexander, the International Development Secretary, apologised profusely when he did appear, five minutes later, for a statement on Burma.

"Could it be that he has been detained advising his sister on the mess that's she's got the government into?" asked Julian Lewis from the Conservative benches.

The Labour Party is in a mess in both parliaments thanks to Mr Alexander's sister. Independence used to be something the SNP obsessed about and Labour simply refused to consider because, it claimed, it had more pressing issues to get on with.

"It's not my politics," said Ms Alexander famously, and her brother might have said that too. But in five short days Ms Alexander has boxed Labour, and a Prime Minister who wraps himself in a Union flag, into a countdown to an independence referendum.

There is, in theory, some merit in putting Alex Salmond on the back foot over the SNP's key policy and in the Holyrood political universe the impact of the English and Welsh local elections and the revolution at City Hall in London may not have had as much impact as the prospect of the SNP's gloating over a year in power. But Ms Alexander's cunning plan backfired on both herself and Gordon Brown in their respective parliaments.

It doesn't matter if her idea of "bring it on" (next week, next year?) is different from Alex Salmond's or Gordon Brown's because Ms Alexander has set in motion events that mean a vote will take place and probably at the time of the SNP's choosing.

There are signs that Labour is preparing the ground for a get-out clause, with a row over the wording of a referendum.

Mr Brown, kicked up his Union Jack kilt by the English electorate, had plenty of pain to get over without reminding everyone of his Caledonian credentials. David Cameron sent Mr Brown another letter yesterday asking just who is in charge. Mr Brown was in Northern Ireland where devolution must seem a straightforward affair compared to the burach in his own backyard.

Deeper down, the Conservatives sense a realignment of politics with Alex Salmond sending out signals that he may do deals with the Tories to Scotland's advantage in a hung Westminster parliament.

After devolution, Scotland all but disappeared from the Westminster political radar but Ms Alexander's intervention brings the constitutional settlement and its attendant baggage - the West Lothian Question, the number of Scots in cabinet, the numerical superiority of the Tory vote in England - crashing back through the portcullis.

Some Labour MPs think Westminster is where the matter should be resolved. "The future of the United Kingdom is core business for the UK parliament," complains Andrew Mackinlay, who has a Scottish sounding name but delights in being English and troublesome.

How does Labour reverse out of this? It is in Gordon Brown's hands to organise a referendum on independence at a time of his choosing through the Westminster parliament. That could restore him as master of his own destiny, but he could just be walking into another beartrap.

Tory backwoodsmen such as Julian Lewis would simply demand another referendum: this time on the European Union constitution.