Don't know the evidence but all kinds of dirt about Johnson is coming out at the moment. This is next weeks chip paper and I bet nothing comes of it. The truth is they are terrified Johnson will win a majority at the next election however they are too stupid to realise this sort of thing helps Johnson with his Johnson plus the people vs the establishment elite narrative
Looks to me that the most important thing for Brexiters is Brexit, no matter what the risks are and Boris and his advisors know that. It's all about winning the votes of the Brexit party, so obvious. Anybody who believes he is fighting for the people against the establishment as he puts it should think a bit. It's all about his election strategy.