What does John Bercow's explosive intervention mean for Brexit?

• Theresa May's government is reeling from John Bercow's bombshell announcement.
• The House of Commons Speaker said on Monday that the prime minister cannot put her Brexit deal to another vote as planned until there are substantial changes to it.
• The UK government is trying to put together a plan B after Bercow left May's strategy in tatters.
• The prime minister is set to ask the European Union for a Brexit delay of up to 12 months.

LONDON - House of Commons Speaker John Bercow on Monday delivered a hammer blow to Theresa May's Brexit plan, announcing that she cannot hold another vote on her deal until there are significant changes to it.

In a move that came to a surprise to virtually everyone in Westminster, including the UK government itself, Bercow said that the prime minister "cannot legitimately" put her deal back to the House of Commons unless it had changed "substantially" since the last time MPs voted on it last week.

That presents another big headache for May, who was considering putting the Withdrawal Agreement back to MPs for third and maybe even a fourth "meaningful vote" in hope of grinding down her opponents and getting a majority.

But that plan seems to be in tatters, and on Tuesday morning May and her most senior ministers will get together for their weekly Cabinet meeting to discuss what on Earth to do next.

Does May have a plan B? And what does Bercow's bombshell mean for Brexit?

A massive spanner in the works for May

Downing Street had hoped that - faced with the prospect of a lengthy delay to Brexit - swathes of staunch pro-Leave Conservatives who have voted against her deal would eventually decide to get on board.

The strategy was to present Eurosceptic MPs with a clear choice: May's deal vs a delayed Brexit.

Bercow's strategy appears to have killed that strategy. No longer are MPs in the European Research Group of pro-Brexit MPs faced with that choice. May's current deal can no longer be the only deal in town.

It also means she will likely have to travel to the latest European Council Summit on Thursday with nothing to show for efforts to persuade MPs to back her beleaguered deal, which has already been rejected twice by huge margins.

Brexiteers are very angry with Bercow

The Express front page on Tuesday branded him "The Brexit Destroyer" while The Sun's declares "B*ll*cks to Bercow."

Bercow has been disliked by the Leave wing of UK politics and Brexit-supporting newspapers since the 2016 referendum.

He is accused of using his powers as House of Commons Chair to further the causes of pro-Remain MPs while making life more difficult for ministers who want to deliver Brexit and MPs who are pushing for a "hard" departure.

This is only latest run-in with Leave MPs. On Monday, he infuriated backbenchers by deciding not to select an amendment which sought to rule out another referendum, despite high levels of cross-party support for the plan.

His backers say that he is effectively carrying out his constitutional duties of maximising the ability of MPs to hold the government to account and preventing ministers having too much power.

Downing Street aides aren't his biggest fans at the moment.

Can the PM get around it?

Downing Street's parliamentary boffins are scurrying around to try find a way of getting around Bercow's bombshell.

Firstly, there is the issue of what constitutes a change to the deal which is "substantially" different. There isn't a concrete definition of what that means in parliamentary terms. Only one man knows: Bercow.

"Everything depends on context and circumstance," Bercow told MPs on Monday. "It has to depend on the circumstances. I would have to look at the specifics. It would be reckless and foolhardy to pronounce in the abstract."

Minister hopes they can argue that a new vote on the deal would be a "substantially" different proposition.

Brexit Secretary Stephen Barclay hinted at this approach on Tuesday morning, telling Sky News: "A number of MPs said they would change their vote, that shows something's different."

However, a handful of MPs changing their minds in Westminster might not be enough.

In perhaps his most revealing response to MPs on Monday, Bercow said that sufficient substantial change would "in all likelihood" have to be a change agreed with the EU: That is, a change to the Brexit deal.

May's ex-legal adviser, Nikki da Costa, has set out other possible cards that her former boss could play.

Writing in The Telegraph, da Costa claims that could use a "paving motion" to prove that there is a House of Commons majority for another meaningful vote despite what Bercow said on Monday.

It is not clear what the government will do in an attempt to outwit Bercow - if anything at all.

"There's no plan yet, everyone is just trying to come to terms with it," a stunned minister told the Guardian on Monday.

So what does this mean for Brexit?

The prime minister is set to ask EU leaders for a long extension to the Article 50 withdrawal process when she meets them in Brussels later this week. May will ask for a Brexit delay of up to one year, according to reports.

This is because under the terms of a government motion passed last week, the prime minister would only ask for a shorter extension of around three months if she could get her deal passed by Wednesday.

Bercow's announcement has torpedoed that possibility.

A longer Brexit delay has major ramifications. It means the UK will all but certainly have to partake in European Parliamentary elections, and might not actually leave the EU until nearly four years after the 2016 referendum.

May will, however, ask for the EU for an "escape" route which means the UK would be able to cut the Article 50 extension short in the event of MPs being persuaded to back the prime minister's deal.

A lengthy Brexit delay also arguably paves the way to a "soft" Brexit.

Bercow on Monday appeared to suggest that he would facilitate votes on alternatives to May's deal.

The prime minister is under intense pressure from all sides to pivot to a softer exit from the EU, potentially the Norway-style "Common Market 2.0" model which is endorsed by MPs across the House of Commons.