A referendum or general election would be the easy justifications for prolongation. Much harder would be time to put together a new proposition (in which May's "red lines" would have to disappear, or it would logically be back to the May-Barnier agreement and therefore a total waste of time).

Why might the EU27 agree to a delay for this? Perhaps because the disruption of a hard Brexit would constitute an external shock to the EU also? Because the EU would want to cover its arse in view of the coming blame game?

The frightening thing is that (given the probable defeat of Corbyn's no confidence motion, the 118 Tories who voted against May yesterday doubtless not relishing the notion of a general election in current circumstances), it's May or another Tory incompetent who'd be in charge of attempting to agree with the EU. Failure and hard Brexit would loom strong.

A second referendum is possible, but dangerous. Resolution would only be obtained if an unquestionably large majority voted one way or the other.

I used to be afew. I'm still not many.