"As Skripal-Gate Collapses, Will May's Government Be Next?" (Luongo).
There is a kind of conspiracy theory which explains the big conspiracies as directed by a council of the ultra-elites, who do the big things when they fear the country - i.e., their personal interests - is in really serious danger and there is no other option. There is huge fear about Brexit and the profits of the banksters in The City, and the (obvious) idea that May simply isn't up to her job. Of course, Boris has situated himself to replace her, and makes no effort to hide his ambitions, and he is even worse, literally a clown.
If you wanted to get rid of both May and Johnson (without, hopefully, leading directly to Corbyn), one (relatively) non-dramatic way would be to hang them out to dry. Get them both to fully commit to a silly and ridiculous anti-Putin conspiracy theory, have them take embarrassing steps following up from the conspiracy theory (and make the issue even bigger and more embarrassing by getting the US and its lackey states to follow along), and then have your intelligence services omit to follow through by failing to murder the two victims while simultaneously failing to back up the 'science' on which the entire silliness is based. Killing the pets, producing a mess of contradictory stories about how the alleged poisoning occurred, stories which aren't even internally consistent, seeming to be unconcerned, even blasé, about the fate of various civilians in potential danger, producing a 'resurrection' of the surely dead victims right around Easter, you couldn't imagine a combination more politically devastating to both May and Johnson.