We now know that the EU is willing to extend the date on which the UK leaves it, at least for a short period. But eventually, one of three things must happen: the UK can leave the EU with a deal, leave with no deal, or not leave.
That third option would involve the UK revoking Article 50 – the section of the Lisbon Treaty which, having been triggered on 29 March 2017, started a two-year countdown to leaving.
A petition calling for that option had been signed by more than three million people by Friday lunchtime.
How could Article 50 be revoked?
The European Court of Justice (ECJ) ruling last year confirmed that the UK could revoke Article 50 itself, without having to ask the other 27