It says here that an independent Swiss lab identified the poison used in the Skripal case...and it is a poison not produced by Russia, but by the USA and the UK.
So, the Russians were telling the truth from the very beginning, and Ms. May was lying.
....which brings us back to the chemical attack in Syria, where the Russians were stating that they had evidence (with witnesses identified by name) that no chemical attack had taken place, and that the fake chemical attack had been staged by UK agents..
So who we gonna believe....