Rants are never very attractive and don't help convince anyone. However, the UK has fairly recent form on making noisy accusations, gathering international support, isolating the victim country, etc. in order to deflect attention from the UK's (government and country) mounting (and embarrassing) problems. But then ultimately, the UK not only failed to crush the country in question but actually lost an international court case which the UK raised as a last ditch attempt at a face-saving measure and was admonished quite firmly (couldn't just back down, of course). That was a Labour government so hopefully this government is not trying to succeed where the others failed - we may never find out the whole truth of the Skripal case.
However, if the Russians are ultimately found not to have done this then the aftermath will be more in the open than the case I refer to above. Then the country under attack was tiny little Iceland and the court outcome was scarcely mentioned in the UK media. Moreover, Iceland is a fellow founding member of NATO and has got used to bullying by the UK (remember the cod wars, all of which the UK lost) and is also used to coming out on top. Russia on the other hand is of a size to be taken seriously and a former cold war adversary. Iceland has now fully recovered from the economic adversity made much worse by the UK and, as before the crash, outperforms the UK on just about all fronts (per capita, not pure size). Icelanders have better lives than Brits, but then that is not so difficult.