Britain will respond decisively if it turns out that Russia is involved in the poisoning in Salisbury of the former GRU officer Sergei Skripal, British Foreign Minister Boris Johnson said.
He called the Kremlin "a malicious and destabilizing force," allowed stricter sanctions against Russia and even a refusal of British representation in the World Cup, which starts in Russia in three months. http://www.bbc.com/russian/news-43305035
There is only a few minor problems in this story: the now allegedly poisoned spy was already in Russian prisons and had then been pardoned and released by Putin, so it is not clear at all why he would years later want to kill him. Even less clear why he would want to do it in a way which would carry his signature, so that the world can blame him. One must be very dumb to believe something like that.
The fact is that this is just a setup which will be used to boycott the Russian Football championship.