Absolute proof of guilt can only be established in a court, which will be impossible as these two are never going to stand trial in this country, but that doesn't stop us as rational human beings realising that the only plausible explanation can be that these chaps and the Russia state are...
What, other than a completely implausable explanation. CCTV of them near to the sripals at the time of the attack and traces of Novichok in their hotel room?!