Theresa May faced a grilling in the Commons this week, with one MP – Labour’s Helen Hayes – reeling off the Prime Minister’s latest u-turns.

“The Prime Minister previously committed to a meaningful vote on her Brexit deal but had to be forced by the courts to hold it.

“She then committed to that meaningful vote in December, but pulled it at the last minute.

“When her deal fell to the worst Government defeat in history, instead of listening to MPs, she carried on regardless, so I ask her: what guarantee, other than her word, will she give this House that we will be able to vote to stop a no-deal Brexit before 29 March?”

Mrs May is no stranger to dramatic shifts in policy – let’s take a look at the most significant.

The meaningful vote

MPs were due to get a “meaningful vote” on the draft withdrawal deal in December. In November, the Prime Minister quipped that a colleague “virtually gave the Leader of the House a heart attack when he suggested delaying the meaningful vote until January”.

But Mrs May did exactly that herself, scrapping the vote a day before it was scheduled to take place.

Just hours before the announcement, Downing Street sources had assured the press that the vote would go ahead as planned – three days earlier Mrs May told her own cabinet that she had no plans to postpone.

No deal off the table?

Mrs May has long argued that leaving the EU without a deal was better than signing up to a “bad deal for Britain”. She dug in her heels when Jeremy Corbyn refused to meet the Prime Minister last month until she took no deal off the table.

But since then, she’s been slowly pivoting her position, and yesterday conceded that MPs will get the chance to vote against no deal if they reject her plans again in March.

When is Brexit happening?

Amidst threats of cabinet walkouts, Theresa May announced yesterday that, if MPs vote down her unpopular deal once more, they’ll be able to seek an extension to Article 50 beyond the current departure date of 29 March.

The mere possibility of delaying Brexit is a major change of direction for a Prime Minister who has uttered the words “29 March” in Parliament no fewer than 121 times according to our search of Hansard.

Should we stay or should we go?

Perhaps Mrs May’s most striking about-turn was on the very question of whether we should leave the EU or not. Campaigning for remain in the run-up to the 2016 referendum, Mrs May said “the economic arguments are clear” and that “being part of a 500 million trading bloc is significant for us”.

In April 2016, in her capacity as then-Home Secretary, Mrs May said that while she expected to continue sharing intelligence in the event of Brexit, “that does not mean we would be as safe as if we remain”.

But just three months later, after the 2016 referendum and during the Conservative leadership campaign, Mrs May dismissed any suggestion that Britain should stay in the EU, and declared: “Brexit means Brexit and we’re going to make a success of it”.

The customs union versus the backstop

Mrs May set out her “red lines” for the Brexit negotiations in January 2017.  They included leaving the customs union – a priority for Brexiteers who say it’s the only way the UK will be able to strike its own free trade deals after Brexit.

But the draft deal Mrs May put to Parliament in November undermines that pledge. It includes a “backstop” that involves the UK staying in the EU customs union, potentially indefinitely, if we can’t strike a trade deal with Brussels in time.

The Prime Minister says that any deal with the EU would require a backstop because both sides are committed to avoiding a hard border in Northern Ireland.

But the particular form her backstop takes – the UK staying in the customs union – could have been avoided if she’s made concessions elsewhere.

She could have accepted Brussels’ offer to allow Northern Ireland to stay part of the EU customs union if no agreement was reached. Mrs May dismissed this option as “unacceptable” because, in her view, it would amount to breaking up the UK. No doubt the staunch opposition from her parliamentary lifeline, the DUP, also weighed on her mind as she considered that proposal.

Whatever brought her there, Mrs May’s planned Brexit deal includes the possibility that the whole UK could remain in the customs union after Brexit – something she explicitly ruled out at the start of negotiations.

Do we have to pay the “divorce bill”?

In September, Mrs May seemed to suggest that the £39 billion “divorce bill” we’ve agreed to pay the EU might be contingent on us leaving with a deal. Asked what would happen if we leave without a deal, she said the “position changes”.

But in November, the Prime Minister said that “there are legal obligations this country would hold to the EU in relation to financial payments in any circumstances”. In other words, the government now considers itself legally bound to pay the divorce bill, whether we get a deal or not. We looked at this in more detail back in January.

The 2017 general election

And of course, things could have been very different for Mrs May had she not made one major volte-face.

In June 2016, she said “there should be no general election until 2020”. That September, she said “I’m not going to be calling a snap election”. But on 18 April 2017, she announced that Britain would be back at the ballot box that summer.

She asked the public to give her a strong mandate to negotiate Brexit, but the plan backfired, as the Conservatives lost their majority in Parliament and were forced to seek a confidence-and-supply arrangement with the DUP.

We’ll never know quite how different things might have been had Mrs May not called the election when she did, but historians of the future will undoubtedly have plenty to say.