Regarding Novichok, personally I reckon that some renegade with a grudge against Skripal from bygone days, obtained a quantity at the time when it was supposed to be being destroyed. Either that or later through an underworld connection.
If Boris-the-bull$hitter, that proven liar (don't take my word for it, just listen to Eddie Mair interviewing the slob), has any real evidence then declare it. Piss or get off the pot, Boris! The juvenile 'russophobia' exhibited by the weak and unstable Tory government appears to have no real justification and simply makes the UK look plain daft.
How the latest exposure to Novichok came about is truly mysterious though. Perhaps the original perpetrator was careless when disposing of the remainder of the substance used in the attempted murder of the Skripals?