Does Glenrothes represent light at the end of the tunnel for Brown?

The simple headline from the Glenrothes by-election - Labour holds on to safe Labour seat with slightly reduced majority - does not begin to hint at the drama of yesterday's vote. Labour's surprise victory over the Scottish National Party is the first evidence that the 'Brown bounce' reported by opinion polls is being translated into real votes at the ballot box.

Two months ago Labour was heading for disaster in the Fife constituency, with even the party's most inveterate optimists dismissing their chances of seeing off a resurgent SNP. It was no coincidence that Labour timed the contest for November 6, hoping its inevitable defeat would be lost amid the hullabaloo over a new US president.

The revival in Gordon Brown's fortunes prompted by his handling of the economic crisis appeared to have come just too late to turn things around in Glenrothes where a formidable SNP machine had blitzed the streets relentlessly. Even 48 hours ago Labour MPs were going around saying the recovery in the party's vote was not enough to see off the SNP forces. One summed it up: "We've got momentum, but it's not enough."

So to win by a respectable margin of 6,737 votes is an amazing turnaround under the circumstances.

There may have been peculiar local circumstances – the local SNP-controlled council faced anger over the sharp increases in home care charges and there may have been some loyalty to Gordon Brown as a Fife boy. But the simple fact remains that Brown, who broke with convention by visiting the by-election campaign twice, has finally proved that Labour can win tricky elections under his leadership.

During the summer it was being speculated that defeat in Glenrothes could deal a fatal blow to his leadership. In fact victory there has given it such an unforeseen fillip that it could have secured his position all the way to the general election. Brown will travel to Washington for next week's economic summit of world leaders (and photos with Barack Obama) with a spring in his step.

His strategy now is continue stalking the world stage, taking the tough decisions and leaving David Cameron to chirrup from the sidelines. For the moment it appears to be working, but no-one in Westminster is fooled. Labour is still about ten points behind the Tories in national polls, enough of a deficit to deliver Downing Street to Cameron with a working majority.

The unknown question is whether that gap will narrow - or widen - when the realities of the economic downturn begin to be felt in the form of lost jobs, home repossessions and business failures. For the moment, though, Brown can see light at the end of the tunnel.

THE MOLE: GLENROTHES BY-ELECTION

LAST UPDATED 7:18 AM, NOVEMBER 7, 2008