19 March 2019updated 07 Jun 2021 12:01pm

Will the EU grant the UK an Article 50 extension?

Anti-Brexit activists fly EU and a Union flag from the Millennium Bridge during a demonstration by fishermen on the River Tyne in Newcastle, northeast England on March 15, 2019, against the terms of the current Brexit deal being offered by Britain's Prime Minister Theresa May. - People working in the fishing industry supported by the pro-Brexit Fishing for Leave organisation, launched a flotilla on Friday in protest against the prospect of Britain continuing to adhere to the EU's Common Fisheries Policy that sets quotas and fishing rights during the transition period after Britain has formally left the European Union. (Photo by Andy Buchanan / AFP) (Photo credit should read ANDY BUCHANAN/AFP/Getty Images)

On Thursday, Theresa May will go to Brussels to request an extension to Article 50 and give the UK more time to decide what it wants.

But an Article 50 extension is not in the powers of European Commission officials in Brussels. It’s a decision that must be taken unanimously by the governments of all 28 EU member states.

Diplomats are stressing that leaders will grant an extension only if there is a clear plan for how it will be used. The EU has made it explicit that it won’t hand over more time to simply continue the fruitless back-and-forth over the backstop. As far as it’s concerned, the exit deal is done and dusted, and it’s the only one currently on the table.

The question that remains is what EU countries would accept as “a clear plan” for a delay. There are some things we know would certainly qualify, such as a second referendum or a general election. Alternatively, if a clear majority of MPs came out in favour of a different kind of Brexit deal – such as one that included membership of a customs union – EU governments are likely to grant the time that’s needed for that to be negotiated. One thing that diplomats are emphasising now is that if the UK sought a long Article 50 extension past July, it would have to hold European Parliament elections in May.

But beyond that, no one knows what will happen when 28 EU heads of government gather around the table on Thursday evening. It depends on what plan Theresa May lays out for the extension – if any. And it depends on the national political considerations that other EU countries have to make. Individual leaders could throw a spanner in the works. French president Emmanuel Macron has said he would demand tough conditions for a long delay; Spanish prime minister Pedro Sánchez, who is facing a general election next month, could see this as the opportune moment to demand concessions on Gibraltar. If there were just one or two dissenting voices, they would more easily be pressured into granting the delay than a larger block of opponents would.

So ultimately, no one yet knows what will fulfil the requirement of “a clear plan” for all 27 EU leaders. It’s much like John Bercow’s ruling yesterday that the government can’t bring back its Brexit deal unless there has been some “meaningful change” to it. What will end up constituting “meaningful change” is up to him, and attempts to predict it are little more than guesswork .