What would be better than a handful of people resigning parties would be if all of the hundreds of MPs opposed to Brexit announced that they would no longer be toeing their parties' lines on that topic.
They should dare their party leaders and whips to suspend them or expel them if they said "We'll be loyal to the party on every single issue except this one. Regarding any other legislation you can count on our votes, but not on this. Now - do you want our votes on all the other things, or do you want to do without them there as well?"
They should dare their party leaders and whips to suspend them or expel them if they said "We'll be loyal to the party on every single issue except this one. Regarding any other legislation you can count on our votes, but not on this. Now - do you want our votes on all the other things, or do you want to do without them there as well?"

