Could the next Prime Minister call an early election?

• It's no longer the case that a Prime Minister can call an early general election with the agreement of the Queen
• The Fixed-term Parliaments Act now sets elections at five-year intervals, with Parliament dissolved automatically
• Early elections can take place if a two-thirds majority of MPs agree, or if the government loses a motion of no confidence and isn't replaced quickly
• These provisions could prove hard to use in practice for a Prime Minister seeking an early election, who may instead be tempted to try to repeal or replace the Fixed-term Parliaments Act

As recently as 2010, the Prime Minister could call a general election at the time that best suited his or her own party, by simply asking the Queen to dissolve Parliament. But he can't any longer. David Cameron's ritual trip to Buckingham Palace when Parliament was dissolved on 30 March was a piece of traditional political theatre—but legally obsolete.

The law decides when elections happen

This is the effect of the Fixed-term Parliaments Act 2011, which sets the date of the next general election for 7 May 2015 and then every five years after that. The Act automatically dissolves Parliament 25 working days beforehand (30 March this time around).

That may seem rather academic, but it matters. This system could have a significant impact on how the next Prime Minister tries to form a working government.

The opinion polls point to a very close election this year, which could lead to a government with only a small majority in the House of Commons—or even a hung Parliament where no one party has a majority at all. This could make it harder for the government to pass the laws it wants. In those circumstances, whoever is Prime Minister may want to call an election quite soon after taking power, to try to secure a more comfortable majority.

His or her problem would be that the Queen no longer has the power to dissolve a Parliament before its five years are up, except in two—and only two—special circumstances described in the Fixed-term Parliaments Act.

Early elections possible, but MPs need to agree

Lord Norton of Louth, an expert in government, has recently lamented that this is still misunderstood, even by political junkies. He points out that an early election can be triggered only if:

• two-thirds of the House of Commons vote for it; or

• a simple majority of MPs (more than half of those voting) passes a specifically worded motion expressing no confidence in the government. In this case, the election can be avoided by a new or reconfigured government securing a vote of confidence within 14 days.

In the event of a hung Parliament, it's been suggested that a Prime Minister seeking an early election could ask MPs to pass a motion of no confidence in their own government and refuse to give a vote of confidence to any alternative government within the 14 days permitted. In those circumstances, polling day would be "appointed by Her Majesty… on the recommendation of the Prime Minister".

The potential worry for a Prime Minister taking this approach is appearing either incompetent or Machiavellian. It might seem more palatable to ask Parliament to amend or repeal the Fixed-term Parliaments Act.

Scrapping the new rules doesn't necessarily bring back the old

Some lawyers think that simply scrapping it would leave a vacuum, rather than the old system of the Prime Minister approaching the Queen being back in force. If that's correct, Parliament would also need to come up with a new law on early elections.

Passing that could take more time than a Prime Minister desperate for an election wants. And if the debate were taking place in a hung Parliament, we can't be sure whether MPs would be able to agree on what should happen in future.