”I wonder if the EU can insist unilaterally that we have another extension, perhaps if they're bombarded by petitioning from an ad hoc "progressive alliance" of MPs. It would be claimed by the Daily Mail as being undemocratic, of course, but Johnson being forced to go along with that would be evidence that he's serious about not leaving with no deal.”

That question was asked a few minutes ago on BBC News. According to a lady from the Institute of Government, they can’t - neither side can act unilaterally, there has to be an approach from one side, and agreement by the other.