A year after the Salisbury poisoning, still no evidence of the use of Novichok was presented to the public.
This is a recurring pro-Kremlin disinformation narrative about Skripal poisoning, one of many competing and contradictory stories promulgated by pro-Kremlin outlets about this case. See here and here for EUvsDisinfo summary of disinformation narratives surrounding Skripal poisoning.
British police have presented a solid chain of evidence about the Skripal case, including pictures, that connects the two suspects to particular locations in the case. Parts of the material have been released to the public. British police and intelligence investigations have produced sufficient hard evidence to charge two Russian nationals for the attack on the Skripals. More British public documents and statements on the case can be found here.
Novichok was developed in Russia in the 1970s and 1980s. It's so unusual, that very few scientists outside of Russia have any real experience in dealing with it and no country outside of Russia is known to have developed the substance. See reports by CNN, BBC, the Guardian.