One year on from events in Salisbury, an official version of what happened reigns supreme: “Russia did it.” This presumption is scandalously short on evidence and logic, but it survives thanks to some highly effective stonewalling by the British government and some apparent media compliance.

The Radio 4’s Today programme last week spoke of “a weight of evidence [against Russia] that even sceptical observers thought was pretty damning”.

Well, not so fast. Some of us “sceptical observers” are still out there, and the official account seems as inconsistent and gap-ridden as it always did – if not more so. Let’s consider, one year on, what we are supposed to believe.

A former Russian double-agent, resident in Salisbury, and his daughter, visiting from Moscow, were poisoned with a lethal nerve-agent, unique to Russia, which was applied to the front-door handle of his house. The pair collapsed a few hours later on a bench in the city centre.

Thanks to the prompt action of the emergency services, the expertise of the defence research establishment at nearby Porton Down, and the care they received at Salisbury General Hospital, they survived what was intended to be a lethal attack. So did a police officer, Det Sgt Nick Bailey, who visited the house soon afterwards.

Skripal attack aftermath – in pictures Show all 15 1 /15 Skripal attack aftermath – in pictures Skripal attack aftermath – in pictures Scene of attack Members of the emergency services in hazard suits fix the tent over the bench where Sergei and Yulia Skripal were found unconscious on a park bench in Salisbury in March 2018. Getty Skripal attack aftermath – in pictures Victim - Sergei Skripal The retired Russian colonel and former double agent for MI6 was in a critical condition in hospital for more than two months after being exposed to novichok in Salisbury. He was given refuge in the UK after being jailed in Moscow for treason. Mr Skripal came to Britain as part of a high-profile “spy swap” in 2010 in which four men were exchanged for ten Russian "sleeper agents" in the US. In this image he is speaking to his lawyer from behind bars in Moscow in 2006. AP Skripal attack aftermath – in pictures Victim - Yulia Skripal Yulia Skripal was struck down by a novichok poison alongside her father Sergei. Facebook Skripal attack aftermath – in pictures Scene of attack A police officer stands guard outside a branch of the Italian chain restaurant Zizzi where the pair dined at before falling ill. It was boarded off whilst investigators worked on the building and later found traces of the chemical weapon within it. AFP/Getty Skripal attack aftermath – in pictures Scene of attack Large areas of central Salisbury were cordoned off by police following the discovery of the Skripals. Traces of nerve agent were also found in The Mill pub. PA Skripal attack aftermath – in pictures Victim - Nick Bailey Detective Sergeant Nick Bailey, rushed to the aid of the Russian ex-spy and his daughter who were targeted with a nerve agent. He was hospitalized after aiding them and didn't leave until three weeks after the attack. Wiltshire Police/Rex Skripal attack aftermath – in pictures Police investigation - Skripal’s home Police believe they were poisoned at home, and detectives found the highest concentration of novichok on the front door of Mr Skripal’s house. Getty Skripal attack aftermath – in pictures Theresa May visits scene of attack Britain's Prime Minister Theresa May spokes with Wiltshire Police's Chief Constable Kier Pritchard near where the Skripal's were found. Britain expelled 23 Russian diplomats over the nerve agent poisoning and suspended high-level contacts, including for the World Cup on March 14. Theresa May told parliament that Russia had failed to respond to her demand for an explanation on how a Soviet-designed chemical, Novichok, was used in Salisbury. AFP/Getty Skripal attack aftermath – in pictures Skripal days before attack Sergei Skripal days before he was exposed to Novichok, that has left him fighting for life. ITV News Skripal attack aftermath – in pictures Police investigation - military involvement British soldiers were deployed soon after the attack to help a counter-terrorism investigation into the nerve agent attack. One of the places they were asked to help out with was Skripal's home and it's surrounding. They were asked to remove a vehicle connected to the agent attack in Salisbury, from a residential street in Gillingham. AFP/Getty Skripal attack aftermath – in pictures Police investigation Personnel in protective coveralls and breathing equipment cover an ambulance with a tarpaulin at the Salisbury District Hospital. AFP/Getty Skripal attack aftermath – in pictures Police investigation The investigation extended to the grave of Sergei Skripal's son Alexander in London Road cemetery. Getty Skripal attack aftermath – in pictures Police investigation The Counter Terrorism Policing Network requested assistance from the military to remove a number of vehicles and objects from Salisbury. EPA Skripal attack aftermath – in pictures Home Secretary visits scene of attack Home Secretary Amber Rudd visited the scene of the nerve agent attack at the Maltings shopping centre on 9 March. Getty Skripal attack aftermath – in pictures Yulia Skripal speaks for the first time Yulia Skripal, speaking for the first time, said she felt lucky to have survived the nerve agent attack in Salisbury which left her fighting for life. Ms Skripal said her life had been “turned upside down” by the assassination attempt. But the Russian national added she hoped to return to her homeland one day, despite the Kremlin being blamed for the attack. Reuters

Four months later, Dawn Sturgess, a woman completely unconnected with the case, died after apparently trying some perfume, picked up from a bin by her partner, which turned out to be novichok in disguise.

Two agents of Russia’s military intelligence service, the GRU, have been identified as suspects – thanks in part to amateur sleuths at an organisation called Bellingcat and in part to CCTV footage. They have been charged with three counts of attempted murder. They have also been charged with killing Sturgess. A third suspect was recently named, who was booked on, but failed to turn up for, the same flight out of the UK as the two GRU agents.

Salisbury is now settling back into a quieter life. The roof of Sergei Skripal’s house has been replaced, and the local police have appealed for information about where the novichok-perfume box might have been between 4 March and 27 June when Dawn Sturgess was poisoned. That is pretty much where things stand now.

So why am I sceptical? What we have here are two, possibly three, dubious-looking Russian suspects, with CCTV, passport and other ID evidence that tracks their movements. We have a motive: Russia would always want to punish a traitor, wouldn’t it? And, aside from a short and entirely scripted appearance by Yuliya, we have a reason why neither of the Skripals has been seen since, despite Russian appeals for consular access: the Skripals need protection from a state that tried to kill them; the UK has a duty to ensure their safety.

All of which might suggest that the case is closed, especially as the prospects of the Russian suspects standing trial in the UK is next to zero. Allowing the Skripal affair to fade into just another example of Russian malevolence would be a travesty, however.

A year later, beyond the knee-jerk presumption of Russian guilt, we see the very same questions that some of us raised at the start.

Why would Russia risk its reputation so close to the World Cup, when it hoped to show a friendlier face to the world? Why would Vladimir Putin jeopardise future spy exchanges by signing off on the assassination of a swapped spy? Why would Russia take eight years to take its vengeance, and choose the very time when Skripal’s daughter was visiting? Other than as a “rogue” operation, none of this made much sense a year ago, and those same doubts remain now.

There is a similar clutch of questions around the suspects. It may have been a botched operation by a branch of Russian intelligence that was losing its touch. But why did it take Bellingcat to apparently reveal the true identity of the agents? Russians must have visas to enter the UK; where did they receive them, for what purpose and in what names? There are flight manifests. The UK authorities could have known within hours who was on what flight in or out of the country.

And why, if these officers had, as we are told, such impressive records, were they staying at a dive in east London? The CCTV evidence tracking them is patchy at best, and we have seen none of the Skripals. Where were they that morning when their mobile phones were switched off? Were they in the house when the door handle was supposedly smeared?

Let’s look, too, at the UK government reaction. Why was it in such a hurry to blame Russia and orchestrate international diplomatic expulsions, when the quality of the information – at least the information so far divulged – looks so deficient? Its own scientists at Porton Down said they could not know where the novichok had come from.

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Put together, these are questions that occur to most people with an interest in the case, and for which there appears to be no satisfactory answer.

And there are more, about the search and decontamination of the house, about the submission of evidence to the chemical weapons watchdog, about the tragic coda of the affair with the death of Dawn Sturgess. The fact that one of the first-responders was the Army’s chief nursing officer adds yet another intriguing footnote.

And then there is the most obvious question. Where are the Skripals? It was hinted early on that they might be given new identities and resettled in a third country. Has that happened? In a recent interview with the Russian media, the UK ambassador in Moscow, Sir Laurie Bristow, insisted they were alive, and did not wish to meet Russian representatives, but he did not say where they were.

In fact, Sir Laurie’s interview, given to the Russian news agency Interfax, repays reading in full, not least for the hope it holds out that both countries might “move on”. But one section on the Skripal case stands out. “We have put a certain amount of information out to the public in the course of the inquiry, but we have not made public everything that we know,” he said. Asked to elucidate, he added: “Of course, we have more information. As I said, that information will eventually be put in front of a court in the UK. We will not make all that information publicly available to the media, because that would prejudice a trial in the UK.”

The problem with this is that Sir Laurie knows as well as anyone that a trial is not going to happen – so this information will never see the light of day. It is therefore reasonable to ask precisely what information is being withheld, and how it would prejudice a trial that will not take place.

With officials repeating the standard line and refusing to engage with even obvious questions (citing “national security” or “intelligence” considerations, of course), others are being left to fill the gaps. Bellingcat has put itself on the map, of course, while bloggers like Rob Slane have tried to question the official narrative.

The difficulties for us sceptics do not end there, because however many questions we raise, the retort comes back: OK, so what do you think happened? And, to be honest, I don’t know.

We may never know for sure but what I feel certain of is that the official version falls some way short of the truth. We are left to piece together a narrative from what we do know. If I were to offer my own possible scenario, it would be along the following lines.

It has seemed to me that both the UK and Russia have known pretty much what happened almost from the beginning, but for reasons of intelligence, embarrassment or whatever, neither is prepared to say. In my view, it may well have been either a failed extraction exercise by the Russians to get Sergei Skripal “home”, or a successful prevention job by the UK that should never have become public.

This would help to explain why Russia’s response – to accusations, expulsions, the naming of the agents, and the “Salisbury tourism” TV interview that smacked of deliberate farce – was far less virulent than might have been expected. The UK’s official version would explain this by saying Russian reticence is simply evidence of Russian guilt. Well, maybe.

Some of the more titillating conspiracy theories link the whole episode to the US election. This version claims that Sergei Skripal was the prime source for the anti-Trump dossier compiled by ex-MI6 officer, Chris Steele. I am reluctant to go this far.