I think that Cameron might have been alluding to the fact that before Brexit can be triggered, parliament must repeal the 1972 European Communities Act by which it voted to take us into the European Union – and MPs have every right, and indeed a duty if they think it best for Britain, to vote to stay.
Article 50 states that “Any member state may decide to withdraw from the Union in accordance with its own constitutional requirements.” The UK’s most fundamental constitutional requirement is that there must first be the approval of its parliament.
So Scotland could remain in both the EU and the UK if the vote in parliament were to fail to repeal the 1972 act - which would almost certainly trigger a General Election, especially if one had not already been held as a result of Boris Johnson becoming leader of the Conservative party.
All rather curious. Like brides left at the altar, after sacrificing their virginity on the promise of marriage, most of the EU governments now want the UK to exit as soon as possible.
Cameron has ruled out the possibility of a second referendum (despite nearly 4 million signatures at this moment) so they can't see any reason for delay.