Finally – a link to a Guardian story – that I can wholeheartedly recommend. (Almost wholeheartedly – there is an anti-Putin aside based on a social media story about Putin confusing a video of US fighting the Taliban with Russian forces fighting ISIS – the writer probably doesn’t understand how documentaries are filmed and that using footage that can be talked about but which may not be the actual footage referred to would be a normal part of making a documentary film – there is no doubt that Russian forces have engaged with ISIS so the comment is off the point).
With that small caveat aside Alexey Kovalev makes the key point. It seems now that either the Kremlin authorised the Skripal attack – or it was an attack by some branch of Russian intelligence and this organ is not on the same page at all as the Kremlin in terms of political and diplomatic strategy for Russia. Neither is a good situation – the latter probably much worse than the former for the West.
Alexey Kovalev is a Russian journalist. He works in Russia. (Once again confirming that it is quite possible to be a critical journalist and work in Russia).
The UK government has said:
We have repeatedly asked Russia to account for what happened in Salisbury in March. Today – just as we have seen throughout – they have responded with obfuscation and lies. 
This is a crude lie. British propaganda. The British government has “asked” nothing. From the very start they pointed a loaded gun at the Russian government and said “confess or… confess”. This point-blank approach would have removed any room for manoeuvre that the Kremlin had at all. One effect of this pressure could (we are still in the realms of speculation) have been to make the Kremlin feel that they should back up whoever did this since they had nothing left to lose. Though this theory can never be tested.