As the Scottish election campaign kicked off officially last week, voters could be forgiven for thinking that it was Gordon Brown fighting for his political life, not Jack McConnell, Scotland’s first minister.

The chancellor has appeared here, there and everywhere, leading Labour’s clawback against an ascendant Scottish National party, even though his beloved devolution was supposed to empower Scottish politicians to do this sort of thing for themselves. Tony Blair flew north, too, and together with Brown stood by the beleaguered McConnell who faces the ignominy of Labour’s first defeat in Scotland in 50 years.

With the SNP ahead in 10 successive opinion polls and only 25 days to go until the election, panic has clearly set in among Labour’s heavyweights.

If current voter intentions turn into actual votes on May 3, the Nats could win as many as 50 of the 129 available seats — not an outright majority but enough to form the next administration at Holyrood. The situation is too grave to be left to a mere local politician; it’s a job for Brown.

This was not what devolution was about. The mantra was Scottish solutions for Scottish problems when Brown, along with almost every other Scottish Labour luminary of his generation, was drawing up the blueprint for the Scotland Act.

But they didn’t factor in the possibility that Labour could become unpopular back home. By inventing a form of proportional representation peculiar to Scotland, devolution’s architects, dominated by Labour and the Liberal Democrats, envisaged coalitions and minority governments but never a separatist Scottish executive. Home rule would, in George Robertson’s famous words, kill independence stone dead.

Now, unless Labour can do a Lazarus, Brown looks set to start his premiership with the spectre of independence haunting him. What a cruel irony that would be: a Scottish prime minister and champion of devolution unable to control Scotland or even count on its support.

Victory for Alex Salmond, the SNP leader, will not break up the union overnight — the SNP has said it will hold a referendum on separation within three years of gaining power. But it will mean the opening of hostilities with London. Salmond has already announced his plans for his first 100 days in office and they make plain his intention to confront London on the return of oil revenues, the siting of Trident on the Clyde, gun control and welfare benefits, among other matters reserved to Westminster.

Brown could see all his dreams of steadfast leadership demolished by Nationalist nitpicking. “This is a recipe for a fight between Scotland and the rest of the UK — a conflict agenda,” he said on one of his Scottish tour dates last week. But Labour has had eight years in Scotland to put its case against the SNP and, as the polls consistently demonstrate, it has failed.

Despite unprecedented levels of public spending, devolution has not lived up to expectations. Uppermost in voters’ minds are the state of hospitals and schools, levels of crime and the lack of bobbies on the beat, and council taxes that have risen by 60% under Labour. All these come under the jurisdiction of the Scottish executive; while ministers may trumpet their achievements, the truth is that they have not delivered on their extravagant pledges.

Wales, which has far more limited devolution than Scotland, has done much better. It has a higher employment growth rate, stronger economic growth, increased manufacturing exports — and Rhodri Morgan, the Welsh first minister, is popular.

Labour in Scotland can blame Blair and the war in Iraq for its poor showing but really it has brought it on itself. Devolution has exposed Scottish Labour at its unreconstructed worst, reluctant to introduce reforms in education and health, doggedly antibusiness and in awe of a massive public sector. It is not surprising that voters should exercise their democratic rights and look for an alternative.

There is no great appetite for independence, according to the polls, but that could change. A Nationalist-led regime could embrace the Liberal Democrats — who refuse to cooperate on a referendum but who are in favour of extra powers for the parliament.

It could also include minority parties, cranks and single-issue zealots who can win seats with alarming ease thanks to proportional representation.

There may be as many as 10 Greens after polling day, possibly a couple of Socialists and assorted maverick independents, all of whom back an independent Scotland, and policies could be as creative as introducing a national wage, ending road building, abandoning the new Forth bridge, scrapping right-to-buy schemes and renationalising the railways, all public transport and Scottish Water.

Like it or not, this is devolution in action, a beast designed by Brown and given life by Blair’s government. How unfortunate for Blair, never a conviction devolutionist, if the process that he set in motion leads to the break-up of Britain and a legacy that outlasts even Iraq.

Far more forlorn will be the figure of Brown as he struggles to push the genie back into the bottle. Having given Scots a hand in running their own affairs, he might have hoped for gratitude. Instead he will get grief.

The Nationalist nightmare threatens to spoil his succession and make it brief, especially if resurgent separatism costs Scottish Labour MPs their seats at the next general election. If Brown can’t command his own kingdom, he may not be able to command the country.

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