Skripal was one of the west's crown jewels (that we know about at least), obvious target. This is about sending a message to potential future-skripals.
And the brazenness of it fits with what I have said - We can get away with this anywhere, you are not safe.
Spies have been killing people for millenia, and the KGB (now FSB) and GRU are particularly good at it. John Barron's book on the KGB from the 70s literally had a list of a few hundred known KGB officers at the back before the index, they all know each other to at least some degree (They'll suss you out the moment you are deployed to a foreign embassy).
> What that aspect is, who knows. But it is probably there.
Like what? Maybe they poisoned themselves with Novichok for a laugh, but it's unlikely. Remember that a lot of Russian money passes through the British ruling party and London so it's not really in their interest to ratfuck
