There was never any doubt that Conservative members would back a UK Prime Minister against a foreign power complicit in murder on British soil. That was not the point of the question.
It was, rather, to dig deeper, and seek to discover if a substantial underbelly of Tory member opinion believes that Russia isn’t a threat to our security and interests. The question isn’t academic. There has been a vogue on parts of the Right to regard the EU as a bigger menace to Britain than Russia. Nigel Farage, for example, expressed this view early last year (well before the attempted murders in Salisbury, for the record).
We have our answer. There is almost no backing at all for that take, at least at the moment. If you are hunting for a pro-Putin fifth column in the UK, you will have to search elsewhere.