The Liberal Democrats have got lucky.

It is not a word one would usually attach to a party running at around seven per cent in the polls.

This is a party whose leader was so hated by the public he was forced to make a humiliating apology to voters two years ago, saying "I'm sorry" in an excruciating video message that, set to music, almost became a chart hit; a party many people across the country have pledged they will never vote for again.

And yet, the LibDems have got lucky. The reason lies both in the kind of party they are and in the kind of General Election we are set to have. Were Labour or the Tories looking like a runaway winner next May, last week's Lib Dem conference in Glasgow would have been a very different affair.

But, unless something dramatic changes, the next General Election will be tight. For a party whose only hope is coalition a close election is necessary. The LibDems also got lucky when they failed to win their referendum to introduce a different voting system, a form of proportional representation, in Westminster elections.

Arguably, if anything saves the party at the next election, it will be the first-past-the-post system, much hated by generations of LibDems. The LibDems are not running a national election. In effect, they are running a series of mini by-elections, trying to keep the 50-plus seats they hold at present. They need voters in those seats to be scared that "the other guy" might be elected. It matters less whether that other guy (they are, after all, all male at present at Westminster) is David Cameron or Ed Miliband.

Expect that message to be hammered home the closer we get to May; but also expect it to become more local. Telling Tory voters in Labour-LibDem marginals that they are the only way to keep Ed Miliband out could help the party pick up votes.

But the same message in Tory-LibDems marginals is only more likely to increase Conservative votes. There are other elements affecting the campaign, of course.

The party thinks the SNP will tack to the left under Nicola Sturgeon, which will help them in some of their more rural constituencies; something, it has to be pointed out, that the Scottish Tories are banking on too. The LibDems also think the shock that Labour got in its heartlands during the referendum campaign will means the party has to spend more time there than in target constituencies such as Jo Swinson's.

The party knows that it will lose seats in 2015. The question is how many. But in this numbers game, the question is also how many seats the other parties take.

The LibDems are playing for coalition and, in a system like Westminster's, that has always depended more on the showing of their opponents than on their own.

Many LibDems are keenly aware that they did not have enough seats to form a coalition with Labour on their own last time around.But they also know that they could just hold the balance of power next time around.

To borrow from Henry Ford, the LibDems are hoping you can have any colour of government you like as long as it is a little bit yellow.