The wider political impact of parliamentary by-elections often turns out to be more important than the actual result – and Eastleigh is likely to be no exception to that rule.

Both the coalition parties saw their share of the vote drop by about a third compared with the 2010 general election.

But because they started ahead, and because they are so well-entrenched on the ground in the constituency, the Lib Dems managed to keep their noses in front.

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Neither Huhne nor Rennard proved to be a sufficiently strong influence on voters to undo years of building up a local organisation and running a well-regarded council.

Since 2010 the Lib Dems have consistently done rather better at the ballot box than in the opinion polls, and Eastleigh confirms that they have simply lost ground rather than been condemned to the electoral scrapheap.

The Tories’ best hope was that their own vote would remain solid, whilst that for the Lib Dems collapsed. That always looked rather unlikely in Eastleigh, but their share of the vote fell to a level last seen at the previous by-election there nearly 20 years ago. They came third then too (behind the Lib Dems and Labour), went on lose the 1997 general election by a country mile, and have not held this seat since.

The real concern for the Tories is that there is no sign that they are making up ground in constituencies which they did not win in 2010 but must do so in 2015 if they are to form a majority government.

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UKIP surpassed its own expectations, and scored well above the level forecast by the various polls conducted during the campaign. Whatever his public pronouncements, Nigel Farage must be kicking himself that he did not stand. Name recognition alone could have been enough to push his party across the line. Yet he should not get too excited.

With Labour still identified with the economic crisis, there really was nowhere else for the traditional by-election protest vote to go. In that sense the coalition has been a gift to UKIP (it took votes from both Tories and Lib Dems) and it now looks likely as if it could press very close for first place nationally at next year’s European Parliament elections fought under proportional representation.

After all, in 2009 it came second behind the Tories and just in front of Labour with 16 percent of the nationwide vote.

Labour Party candidate John O'Farrell. Credit: Press Association

Even first place in 2014 will not mean that UKIP is poised to elect MPs in 2015 though.

A general election focuses voters’ minds on whom they want to run the country (and Cameron’s pitch then will be that only a Tory government will have the resolve to deliver the promised EU referendum) and previous by-election dramas are often forgotten.

In 1993, for example, the Lib Dems won Christchurch in Dorset from the Tories with 62 percent of the vote – more than twice what UKIP achieved yesterday, but lost it again four years later.

Labour rather sat this by-election out.

They had their own success against the Tories in Corby back in November, and in many ways were content to watch the coalition tear itself apart from the side lines.

The party knows it has to make gains in the south of England in 2015, but seats like Eastleigh are no longer on its radar.

The result does demonstrate though that the electoral pendulum no longer swings in a predictable way and Labour cannot simply count on government unpopularity as its path back to power.

Eastleigh by-election results

  • Mike Thornton (Liberal Democrat) - 13,342 - 32.1%

  • Diane James (UKIP) - 11,571 - 27.8%

  • Maria Hutchings (Conservative) - 10,559 - 25.4%

  • John O'Farrell (Labour) - 4,088 - 9.8%

  • Others - 4.9%