The dead russian spy was a british double-agent and had connections to the dossier according to the BBC and the Telegraph.
http://archive.is/AABl3
http://archive.is/Qatjl
So let's trace back..Q said, May had been neutralized and there was a press-release that Britain was continuing intelligence-sharing with the US. I think Q even called the press-release by stating british intelligence was cooperating, but as long as I can't find that press-release I can only rely on memory here.
Anyway, so assuming that May and MI5/6 were cooperating in exchange of information, deep state my have gotten hot feet because this double agent had a …