“Make no mistake,” Andy Sawford beamed, “since this constituency existed, no party has formed a government without winning here.”

The seat has been with the biggest party at every election since its creation in 1983, most marginally in 1992, but also narrowly in 1987 and 2010. But has does his victory herald a breakthrough for Ed Miliband’s rebranded One Nation Labour Party?

Sawford won 17,267 votes for Labour, a respectable 48 per cent, on a healthy by-election turnout of 45 per cent.

Louise Mensch, his controversial Tory predecessor, who even before the polls closed was taking the blame, may well have been a factor in her successor Christine Emmett’s defeat. But everywhere you went in Corby there was just one issue – jobs.

With little good news on growth, Sawford was pushing at an open door with his alternative economic message. He was also first out of the blocks, returning from his summer holiday to start campaigning when Mensch resigned in August. The Conservatives delayed choosing their candidate and also had to fend off false-start rumours of big name contestants, such as Boris Johnson.

Labour’s main enemy would have been complacency so Sawford and Miliband continually urged their supporters to turn out, even in the face of polling by arch-Tory Lord Ashcroft, showing Labour with a 22 point lead.

Labour organised well, campaigned hard and as Cameron suggested, had the easier task of throwing the stones, rather than batting them back. They may also have hoovered up some of the 5,000 or so voters who had deserted the Lib Dems since 2010.

So although the turnout was more than 20 per cent down on the general election, Sawford’s number and percentage of votes would seem to indicate if he covers the ground well he can hang on to the seat in 2015, as well as offering his party welcome momentum right now.

But another factor lurks in the background to give the Conservatives something else to worry about – UKIP.

Nigel Farage was the only party leader at the count and his presence was not merely a convenience, following his appearance on the BBC’s Question Time in the Northamptonshire town the previous day. The UKIP leader braved a return to the county that was the scene of his serious plane crash two years ago to join in his party’s best-ever by-election performance.

And while celebrating his party’s 5,108 votes, almost three times the Lib Dem total, Farage confided he felt this election was the one in which UKIP crossed over into mainstream politics, stopped being one-issue anti-Europeans and started becoming known for its stance on other issues judged important by mainstream voters.

So Corby may have lasting significance in providing the first evidence of a potential perfect storm for the Conservatives of increasing Labour momentum in an era of disappointing economic news, combined with UKIP starting to offer a threat beyond its previous single issue politics to the Tory right flank.

Unless the economy dramatically improves by May 2015, Corby may come to be seen as the point at which Ed Miliband’s One Nation Labour joined Andy Sawford in travelling down the A6003, the road which really does run through Corby towards Downing Street.

Tor Clark is Principal Lecturer in Journalism at De Montfort University in Leicester

Tags: Andy Sawford, Corby by-election, Louise Mensch, Nigel Farage, One Nation Labour