The Prime Minister's decision to call a snap election

She said she wouldn’t do it, for good reasons. She has now done it, for even better ones – even if some remain unspoken. In calling a snap general election despite all her professions that she would not do just that, Theresa May put the prime blame on other parties and the House of Lords, where it lies with even more justification on her own party.

She was right: this snap election represents by far her best chance of eventually securing parliamentary approval for the kind of compromise deal on Brexit that would avoid the hardest of exits – with no deal at all. Since the Prime Minister exercised Article 50 on 29 March, it has become clear that the European Union (EU) will demand significant compromises if Britain is to secure a deal of any shape.

There are at least 50 MPs in her party for whom (if we take them at their word) this would be anathema, and would vote down such a deal even if it meant that Britain would leave the EU with no deal at all. She did not mention them in her statement, preferring to focus on the Labour, Liberal Democrat and Scottish National Party (SNP) MPs with their assorted reasons for objecting to a likely deal, as well as to likely opposition in the Lords. But they are surely the greater obstacle. 

Two more factors will have influenced this decision. One is that the past few months have made starkly clear the need for a generous “implementation phase” to get from the status quo to future arrangements. The Prime Minister and her advisers have begun to use this phrase freely to begin to build support for the notion (though it is again regarded with suspicion by many of the hardest Brexiteers, just in case the transition never ends).

The quiet – but hugely valuable – benefit of winning a general election this year would be to move the next general election to the other side of those badly-needed years for making the transition to life after Brexit.

The second, more obvious factor, brought to a head by two opinion polls over the Easter weekend, was that Labour appears to be more than 20 points behind the Conservatives (although a third poll put the gap at less than half that distance).

The Prime Minister appears to have won her first gamble – with the Opposition leader, Jeremy Corbyn, saying he will not oppose an early election, she is guaranteed the two-thirds majority she needs to call an early election despite the Fixed-term Parliaments Act.

It is conceivable that an early election could strengthen the SNP’s hand in its campaign for a second independence referendum. If the party, campaigning on its anti-Brexit platform, achieved another clean sweep of seats, its case would appear to be stronger.

And uncertainty is an inescapable part of holding elections, as the Prime Minister pointed out in the long months while she was resisting the blandishments of party grandees (such as William Hague, former Foreign Secretary, now a Conservative peer) to do just that. Her arguments, as relayed by those close to her, were that she disliked the distraction and felt that voters would hold it against her if she was seen to be “playing politics”.

What voters do will depend partly on whether they see this election as necessary to address the rifts in the Conservative Party – as David Cameron felt the EU referendum itself to be – or whether they accept the message she took pains to stress in her statement: that other parties and the Lords would prevent her offering to the country the Brexit deal she thought best for Britain’s future.

She had good arguments for resisting. But three changes in the past three months – the EU’s demands for compromise, the clear need for an implementation phase and Labour’s enduring and tantalising weakness – made the case for a U-turn irresistible.