Caporegime
I dont think Boris is trying to do this for the leadership... DC is leaving at the end of the current term and there is no competition at the moment, so all he'd have to do is wait?
I'm skeptical that Dave actually will go as he said he would - wouldn't be the first promise he's broken. George Osborne is the heir apparent and imo will become PM if indeed DC does quit and we vote to stay in the EU.