The High Court judgement granting permission for blood samples to be taken from the Skripals for testing by the OPCW contains some interesting information, not least the relevant evidence from scientists at Porton Down that their own analysis of blood samples 'indicated exposure to a nerve agent
or related compound. The samples tested positive for the presence of a Novichok class nerve agent
or closely related agent' (my emphasis). PD's language is cautious (obviously: they're scientists not politicians) and consistent with the, oft-repeated, line that the agent was 'of a type developed by Russia.' But May, Johnson et al have, as politicians with ulterior motives are wont to do, bullheadedly charged ahead of any existing evidence that will support their increasingly wild snortings.
https://www.judiciary.gov.uk/wp-content/uploads/2018/03/sshd-v-skripal-and-another-20180322.pdf