Why wouldn't the UK do it.... ? Motive means and opportunity.... Motive --- the military want more money and Russia is always the convenient reason why Means --- Porton Down not very far away -jeeez  they could even have used the 'victims' as guinea pigs for a new biological weapon - * Opportunity ---- Porton Down close enough to get it all done with minimal risk and planning -    https://www.thetimes.co.uk/article/spy-mystery-rare-poison-may-be-traced-to-single-lab-skripa