This will be a Brexit general election in every sense of the word. Although the parties will talk about the economy and public services, Theresa May will turn it into a referendum on her vision for Brexit and “getting on with the job” of implementing the people’s decision last year.

In her surprise statement, she positioned herself as the anti-Westminster champion who is taking on those MPs and peers who want to block or water down Brexit. It is quite an achievement for a Prime Minister to pose as the anti-establishment candidate.

The Liberal Democrats and the SNP will fight the election on a platform of opposing the hard Brexit offered by May, who has made clear the UK would leave the single market and customs union under her strategy. But Labour under Jeremy Corbyn will be unlikely to fall into that trap – for fear of alienating working-class voters in the North and Midlands, who might switch to the Conservatives or even Ukip.

Corbyn has already said Labour will fight on the economy, living standards, the NHS and schools. His commitment today to “a Brexit that works for all” was deliberately vague. He will calculate that he will keep most of the middle-class pro-EU Labour vote angered by his support for triggering the Article 50 negotiations, although some of it could be lost to the resurgent Lib Dems. Tim Farron’s party, with just nine MPs, has nothing to lose by sticking to its guns and fighting on a “stop hard Brexit” ticket.

Theresa May calls general election for June 8

Although May used Brexit to justify her remarkable U-turn, there was, of course, another reason why she changed her mind: a string of opinion polls showing the Conservatives 20 points or more ahead of Labour and her commanding lead over Corbyn as the best prime minister. She knows she will never have a better opportunity to turn her slender majority into a three-figure one, or enjoy such weak opposition.

However, the move is not without risks for May. Tory officials are nervous about the Lib Dem recovery in the South-west, where the Tories won many seats from the Lib Dems at the 2015 election. But May’s prospects of winning a bigger majority are strong.

The temptation to win a big majority – to make it much easier to push through both Brexit and her domestic agenda – was too good to miss. May calculated that Parliament could seriously constrain her freedom to negotiate the Brexit she sees fit as the talks progress.

At present, there is no majority in the House of Commons or Lords for a hard Brexit. If May wins a bigger majority, she will claim a people’s mandate for her hard Brexit. The growing prospect of a soft Brexit alliance between pro-EU Tories, Labour, the Lib Dems and SNP is likely to be demolished in one fell swoop on 8 June.

May’s move makes hard Brexit much more likely. Loyalty has always been the Tories’ secret weapon. The 30 pro-EU Tory MPs will be reluctant to defy May’s line during the election. They would be much less likely to fight for soft Brexit if she has won a personal mandate.

The Lords will still have a soft Brexit majority. Peers will doubtless put pressure on May, but without significant backing in the Commons, the “unelected second chamber” will be powerless to halt hard Brexit.

The unexpected election will not have much immediate impact on the Brexit negotiations due to start next month. There is a small window of opportunity before they begin in earnest; UK ministers have always maintained that the big decisions would not be taken until after the German elections in the autumn.

Times Theresa May has said there won't be an election until 2020

A bigger majority would strengthen May’s hand in the arm-wrestling that lies ahead. That is the way elections work in the EU. The EU 27 would have to treat her with more respect – and not as someone who, as Nicola Sturgeon recently reminded May, had never won a personal mandate.

May wants an EU deal. An election win would give her more room to make the concessions she has signalled recently – on a divorce bill for the UK of up to £50bn, continuing freedom of movement and a remit for European Court of Justices during a transitional period. It would be more difficult for hard-line Brexiteer Tories to oppose such concessions.

The absence of an election on the original timetable of 2020 will make it easier for May to win domestic approval for a transitional deal to smooth the exit process, notably for business. She might even be able to win a longer transitional process, although the European Parliament has called for a three-year limit. May will be able to avoid criticism from hardline Brexiteers and their newspaper allies at a 2020 election that the UK had not really left the EU and was still half-in, half-out.