The last straw for me was when Theresa May declared, without any doubt, that the Russian state had attempted to assassinate two British citizens using nerve agents (10 days after the fact, before the conclusion of any investigation and without any concrete evidence to implicate Russia).
I don't follow you here. The toxin in question is known, or at least widely assumed, to be produced and controlled exclusively by state-sanctioned facilities in Russia.
So, scenario one is that Putin's agents committed the assassination attempt. That's obviously bad.
Scenario two is that Putin has lost control of his country's WMDs, and that they are being deployed in foreign countries by rogue actors without his permission. That's arguably even worse.
So, which is more likely, in your opinion?