Lets Get Real:
IF the PM invokes Article 16, then the noise in opposition will come from the House of Lords, its full of REMAINERS, who have never gotten over the fact that the UK has voted to leave the EU and wants a limited relationship with that body. As the House of Commons can over rule the House of Lords that should not be a problem, there a few REMAINERS still in the Commons but not as much after the PM did a political cull before the 2019 General Election. Also even some young MPs know that going against the PM on this will surly rule them out for future jobs in the Cabinet even the top job itself. The Courts are another problem, the House of Commons has to be FIRM with them, the House of Commons decides the LAW, it is up to the Courts to interoperate them, in the old days the King or Queen could just put irritant people in the Tower of London, but we are modern, no cushy seats in the House of Lords if they pull a stunt in favour of the EU. Politics is a tough business, sometimes you have to show the power.