In particular, he asked the Prime Minister if tests had been done on the nerve agent at Porton Down to try to identify its origin and those responsible:

“Has high-resolution trace analysis been run on a sample of the nerve agent, and has that revealed any evidence as to the location of its production or the identity of its perpetrators?”

An answer to that question would have revealed that Porton Down scientists were unable to establish the location of the agent’s production. On 27 September 2017, the OPCW Director-General, Ahmet Üzümcü, congratulated Russia in the following terms:

“The completion of the verified destruction of Russia's chemical weapons programme is a major milestone in the achievement of the goals of the Chemical Weapons Convention. Moscow convened the meeting at the Hague of the Organisation for the Prohibition of Chemical Weapons’ decision-making executive to counter accusations by Britain that it was behind the March 4th poisoning of Sergei Skripal and his daughter Yulia with a military-grade nerve toxin in the English city of Salisbury. The Foreign Office accused Russia of attempting to undermine the work of the OPCW and engaging in “another diversionary tactic”. Scientists at the Porton Down biological and chemical weapons laboratory in England have concluded that the toxin was among a category of Soviet-era nerve agents called Novichok, though they could not yet determine whether it was made in Russia. A Foreign Office spokesman said: “Russia has called this meeting to undermine the work of the OPCW, which, fully in accordance with the chemical weapons convention, is providing the UK with technical assistance and evaluation through independent analysis of samples from the Salisbury attack. “This Russian initiative is yet again another diversionary tactic, intended to undermine the work of the OPCW in reaching a conclusion.”

Wednesday’s meeting of the OPCW executive council at The Hague will be held behind closed doors. “Based on the positive identification of this chemical agent by world-leading experts at the Defence Science and Technology Laboratory at Porton Down, our knowledge that Russia has previously produced this agent and would still be capable of doing so, Russia’s record of conducting state-sponsored assassinations and our assessment that Russia views some defectors as legitimate targets for assassinations, the Government have concluded that it is highly likely that Russia was responsible for the act against Sergei and Yulia Skripal.”

That is a heroic effort to connect the Russian state with the attempted assassinations, but it is almost entirely devoid of facts that do so.
Russia requests for the United Kingdom to release "every possible element of evidence" proving Russian involvement and requests the Executive Council of the Organisation for the Prohibition of Chemical Weapons to call a special session tomorrow.