Slowly the attack is getting clearer and may no longer have been a public event - rather than the Skripal pair were poisoned in their private house:
Asked if there were any leads in the case, Lord Blair told the Today Programme on Radio 4: “There are some indications that the police officer who was injured had been to the house, whereas there was a doctor who looked after the patients in the open, who hasn’t been affected at all. So there maybe some clues floating around in here."
Link:https://www.telegraph.co.uk/news/201...olice-believe/

Lord Blair being a former Met Police Commissioner till 2008 and one assumes he was able to network to come out with this.