There has not been a coalition government in Britain since the Second World War, but it may have to get used to them. The election on May 6 left both major parties—the Conservatives and Labour—short of a majority, and put history’s also-rans, the Liberal Democratic Party, in the position of king-maker. It has used that position very cleverly, and Britain may be heading for a major constitutional change.

Nick Clegg, the Liberal Democratic leader, used the five days of hectic negotiations after the election to extract a high price from the Conservative Party for agreeing to enter a coalition with them. Policy differences on taxes or educational policy could be finessed fairly easily, but Clegg’s bottom line was electoral reform. That used to be a Conservative red line—but in the end they crossed it.

Electoral reform? Who cares about that except a few policy wonks? Well, no: the Liberal Democrats care passionately about it. It’s the only way that they can ever fight their way back into the centre ring of politics.

The Lib Dems’ political ancestors are the Liberals and, before them, the Whigs. For more than two centuries that lineage provided one of the two great parties that alternated in power in Britain. Then in the 1920s, with the rise of the Labour Party, the Liberals came third in one election—and never found their way back to power.

The winner-take-all British electoral system (“first-past-the-post”) is cruelly unfair to third parties. In the election just past, the Lib Dems got almost a quarter of the votes—but less than a tenth of the seats in parliament. So many people saw a vote for them as a wasted vote, even if they liked their ideas.

It was a vicious circle, so for many decades now the most urgent tactical goal of the Libs Dems has been to change the voting system. Alternative vote, “alternative vote plus”, proportional representation—anything that gave them a fair chance of winning.

The two “major” parties, the beneficiaries of the existing system, naturally resisted any change in the electoral rules. The only way it could ever happen is if both of them had to beg for the support of the Lib Dems. Like now.

Lib Dem leader Nick Clegg would have preferred a coalition with Labour, since most Lib Dem voters are more or less on the left. But he rightly said that he had to talk to the Conservatives first, since they had ended up with more seats than Labour after the election on May 6—and he also knew that Labour would be an even less trustworthy partner in power than the Conservatives.

Former prime minister Gordon Brown tried hard to make a deal with the Lib Dems that would keep the Labour Party in power, but his party, aware of the savage cuts that any incoming government would have to make to deal with a runaway budget deficit, didn’t agree. Many of them thought that this was a good election to lose—so Brown’s prospective coalition partners, the Liberal Democrats, could not trust Labour to keep any deal he made.

A senior Liberal Democrat, discussing the parallel negotiations that the Lib Dems conducted with Labour, explained that though the talks were amicable, “problems remain on deliverability and Labour cohesion". In other words, some Labour members of parliament would rebel against the deal, probably sooner rather than later—and since a Lib-Lab coalition would have the slimmest of majorities, just a few rebels could bring the coalition down.

Prime Minister David Cameron, on the other hand, may come to rue the day when he agreed to the terms of the deal that finally put him in office.

Cameron was not well liked by large sectors of the Conservative Party that he leads even before the election: he was a “modernizer”, and Conservatives are conservative. But he is more actively disliked now, because many senior members of the party (and probably most of the rank and file) blame him for failing to pull off a clear win against a Labour Party that was exhausted and partly discredited after thirteen years in power.

They thought they were cruising smoothly to victory, and they wound up twenty seats short of a majority. They accepted the extortionate concessions that the Liberal Democrats demanded for a coalition because after 13 years in the wilderness they were positively panting with eagerness to be in government again. But when the going gets rough, they will blame Cameron for those concessions, too.

The biggest concession was of course a promise to the Lib Dems to hold a referendum on changing the electoral system. Labour made a similar promise, but in the assessment of the Lib Dems a coalition with Labour would not survive long enough to get the legislation through, so they ended the Lib-Lab talks.

The Conservative-Liberal Democratic coalition, on the other hand, has a big enough majority in parliament that it cannot be brought down by just a few rebels from either party. It could actually last four years, which would be long enough to change the voting system (if the voters agree, and current opinion polls suggest that they would).

That is the Lib Dem strategy. If it succeeds, coalition governments will become the norm in Britain.

Gwynne Dyer is a London-based independent journalist whose articles are published in 45 countries.