The explanation by the two suspects in the Sergei Skripal poisoning for their presence in Salisbury in March – a sightseeing holiday diverted by snow – is so implausible that it raises intriguing questions about why Russia chose this alibi and what it says about the health of the state’s propaganda machine.

It is possible the propagandists are so inured to lying without consequence that they genuinely thought the explanation would fly. But if this was an attempt to sow western suspicion that MI6 had got the wrong men, the interview will have had the opposite effect. There will be a small constituency in Britain who think the men’s visit to Salisbury on the weekend of the poisoning was genuinely a fantastical coincidence. But they will be a tiny minority.

Moscow on this analysis is simply more amateur and clumsy than many imagined. An alternative explanation is that Moscow regards the whole Skripal episode simply as an opportunity to troll the British and show that Russia does not care what London thinks.

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But that is not how Russia has behaved in diplomatic circles in recent months. The icy contempt for the UK is genuine, but at the UN security council, Russian diplomats have made strenuous efforts to challenge the UK claims, offer alternative explanations and court swing opinion. Use of chemical weapons is a touchstone issue at the UN, and on this Russia would not want pariah status.

A third, and probably most plausible, explanation is that the interview was designed primarily for consumption in Russia. The British police accusations, including the CCTV footage, have been widely publicised in Russian media, and some form of counter-narrative for such a bungled and exposed operation was required.

Certainly, British officials had thought Vladimir Putin would not respond to the findings of the police inquiry. A brazen Moscow would simply deny any knowledge of the men’s existence, denounce the CCTV footage as fabricated and shut up shop.

That Putin chose not to do so, and instead allow Russia Today to conduct an interview translated into English, shows a certain nervousness. The UK Foreign Office, not surprisingly, was scathing, saying: “We have repeatedly asked Russia to account for what happened in Salisbury in March. Today, just as we have seen throughout, they have responded with obfuscation and lies.”

The Russian explanation indeed is so weak it is likely only to help Foreign Office efforts to persuade Europe to take a stronger line on sanctions against countries that use chemical weapons. Russia will counter that the explanation is plausible and that the UK has been no more forthcoming in allowing Sergei Skripal and his daughter to undertake any forensic interview.

Brief interviews by Reuters and handwritten statements are all that have been provided by the intelligence services, which argue that the two need to be protected and have not yet fully recovered medically.

It will remain a matter of regret that British intelligence did not have CCTV outside the Skripal family home, probably the only way any Russian agents could have been filmed in the act of poisoning. Russia’s explanation, however, is the next best thing.