Why Vote Leave's immigration policy means a move against Cameron

This policy is about more than just immigration, it's about competing visions of a post Brexit Britain, and who might lead it.

'Vote Leave' want to place the same restrictions on EU migrants as on those from the rest of the world.

That effectively means they want to leave not only the EU but also the European Economic Area membership of which requires the free movement of workers.

'Remain's' principle argument for staying inside the EU is an economic one. It seems clear that even in the event of Brexit they would want to stay inside the EEA.

Post Brexit the current Tory leadership (and a majority in Parliament) would favour remaining in the EEA.

So to get his immigration policy through Boris Johnson must first win the referendum, then persuade the Conservative Party to support exit from the EEA as well.

Will he get that past a Prime Minister who has just campaigned on staying in?

I don't think so. I think he would have to get rid of him first.