@JohnM: we're cross-posting and writing at the same time! So, I'll leave it there and go and watch some TV...
The UK doesn't have a constitution and Parliament is governed by obscure rules & regulations. They are mostly Oxbridge gobshites used to debating chambers and taking shite at dinner parties. If the 'rebels' want to find a way, they'll maybe find a line in a paragraph from some obscure 1842 parliamentary debate that gives them the go-ahead.
But I think the ball is in BJ's court. The
British English, lied to by the
British tabloid press, seem to want to jump off the cliff so they can get rid of 'dem foreigners' & restore the white cliffs of Dover to the right shade of white
The funny thing is I was watching BBC news this morning and they were having a 'farming week'. They interviewed a farmer who grows strawberries. He was talking up his superior British strawberries and how the British loved British strawberries. He was worried that after Brexit, the 30,0000 foreigners needed to pick them (nationwide) wouldn't be allowed in to pick them. Nobody noticed the irony!