2015 election – the next big ballot box surprise?

Welcome back to 1974. A tight spring election fails to produce a majority for either of the main parties, so the prime minster of the new minority government calls a second poll in the autumn in pursuit of a clear mandate. Predictions for 2015 are, of course, foolhardy. A small majority for either of the main parties remains possible, as does another two-party coalition. But most forecasts point towards no overall majority, with both Labour and Conservatives failing to reach the magic 326 seats. If neither is able to forge a coalition, or agree a confidence-and-supply deal with other parties, a shaky minority government will, as in 1974, be the result.

The casual assumption is that this will give way to another election soon after. Leading pundits increasingly repeat this line: the Conservatives are said to be already fundraising for a snap second poll; and the bookies are shortening the odds on it.

Well, if you are tempted to have a flutter, spend a moment reflecting on the 2011 Fixed-term Parliaments Act.

This law, introduced in the early days of the coalition, shook up our constitution and fixed parliamentary terms at five years. It stipulates that either two-thirds of MPs need to vote for a dissolution or there must be a vote of no confidence in the government, followed by a two-week period in which no alternative administration emerges capable of surviving a confidence vote. The end of that process triggers a general election.

Under certain circumstances this is likely to make a second election dramatically less likely than it used to be. Sure, if the opposition party isn’t close to being able to form a government, the law might be largely irrelevant: a determined prime minister could probably still find a way of triggering an early election – by resigning, for example. But if the opposition has almost as many seats as the governing party and an alternative government is plausible, the leader of the opposition could have an effective veto on whether a second election is called.

Consider how this might play out. A new minority administration with barely more seats than the opposition would have to continually improvise and strike deals with other parties to get each Queen’s speech and budget passed. That’s perfectly possible of course – as Alex Salmond artfully demonstrated in his first term as Scottish first minister. But at some point the deals may dry up as the small parties sense they could get bigger concessions from an alternative administration.

Previously the threat of an early and unwelcome election has been a powerful force keeping smaller parties at the table. But an opposition that is determined to avoid a second election – a demoralised and bankrupted Labour party post-May, or a Tory party thrown into chaos by a bloody leadership contest – has the option not only of dodging an election but also attempting to move into Downing Street themselves.

It would, of course, be audacious and highly risky. But an opposition hungry for a stint in No 10 would have a very large incentive to make some attractive offers to MPs from small parties. And after May, there will be more of such MPs with whom to trade.

If this were to happen the electorate would become bystanders as a voteless transfer of power took place. It would throw a match on the dry tinder of popular concern over how Westminster politics is conducted.

True, not every change at Downing Street has been preceded by an election: witness Brown, Major, Callaghan and Douglas-Home. And sometimes the political character of a government has changed as a new minority partner has bene introduced, such as the formation of the Lib-Lab pact in 1977. But there is no precedent for changing the main governing party without an election (excluding the PM of the day resigning as Stanley Baldwin did in 1924) – a practice more in keeping with the French 4th Republic than a modern liberal democracy. It’s this scenario, which tight opinion polls are bringing into focus, which is the prime reason our leading constitutional expert Vernon Bogdanor had profound misgivings about the fixed-term act in the first place. Indeed, a voteless change in government would be such a breach with democratic custom that it’s still hard to imagine it happening.

For a start, the difficulty of securing a second poll following a dead-heat election in May might well make it more likely that the leader of a minority government would go the extra mile to forge a coalition in the first place. Or if a minority government sensed that the opposition parties were starting to manoeuvre it might take the extraordinary step of urgently engineering a vote of no confidence in itself in order to trigger a pre-emptive election before their opponents were ready to strike.

Perhaps the biggest caveat of all is that an opposition leader seeking to enter No 10 through the unelected back door would face a media blitzkrieg. Toughing out a full-scale constitutional storm for two weeks before the second vote of confidence would be an epic test of party discipline. And, even if they pulled it off, what sort of mandate would the new PM actually have?

The broader point is that the fixed-term act was constructed to glue the Conservatives and Lib Dems together, and to be a force for stability in an era of two-party coalitions. But that assumption is already looking jaded. If, over the course of five years, our model of politics has shifted from being a stable two-party affair to a more fluid multiparty contest then the fixed-term parliament rules (at least in their current form) have the potential to become a force for democratic instability.

Whether this constitutional possibility becomes political reality depends among other things on the precise parliamentary arithmetic after 7 May. But we certainly face a tight and unpredictable election against the backdrop of a new, untested and poorly understood constitutional settlement.

This article originally appeared in The Guardian.