It is now more than seven months since assassins from Russia’s military intelligence service tried to kill a former double agent and his daughter with a nerve agent in Salisbury. Or did they? The only incontrovertible fact in that assertion is the location, Salisbury. Pretty much everything else remains speculative.

The Skripal case has troubled me since the first news broke in March. It is not the improbability of what was reported to have happened – improbable things are the stuff of news. It is rather the mixture of utter certainty, unsubstantiated claims and glaring information gaps that is so disconcerting, from the immediate rush by UK officials to blame the Russian state, to the way the main figures in this drama have simply vanished, and now to the contradictions that have gained blithe, and almost universal, acceptance.

When the Metropolitan Police showed the passports of two Russians they believed to be the assassins, they strongly hinted that the names on the documents were false. The invitation to establish their real names was taken up by investigative organisation Bellingcat, which has now – amid a blizzard of documentation, seductive reference to “open source” techniques, and not a little help from Russian whistleblowers – come up with what it says are their real identities.

One of them is Colonel Anatoly Chepiga; the other is a medically qualified agent called Alexander Mishkin, and both have received state honours from President Putin.

What’s so suspect about this, you may ask. Well, let’s start with Bellingcat, which has presented itself in the past as a microcosm of well-meaning and very British amateurishness, based in a Leicestershire bedroom, producing results that put the professional sleuths to shame. In fact, Bellingcat has grown rather a lot beyond its shoestring origins. It has money – where from? It has been hiring staff. It has transatlantic connections. It has never, so far as I am aware, reached any conclusion – whether on the downing of the Malaysian plane over eastern Ukraine, or chemical weapons use in Syria, or now, with the Skripals – that is in any way inconvenient to the UK or US authorities.

That need not cast doubt on its findings. But should the authenticity of the documents it cites not be subject, at very least, to the same scrutiny as might be applied to other evidence? And when, as this week, UK officials say they do not “dispute” Bellingcat’s identification of Chepiga and Mishkin, does this not prompt a few questions about whether, say, our “agencies” reached the same conclusions long ago, but kept quiet, or why most of the UK’s media apparently find Bellingcat a more trustworthy source than the UK intelligence services (possible answer: Iraq)? Might not the group’s good name be being used to get information into the public domain that officials do not want to vouch for? And, if so, would this be to inform, or to mislead?

What else do I find troubling? How about the UK and US focus on Russian military intelligence, still referred to as the GRU? I don’t recall any specific Soviet or Russian agency being so clearly fingered in this way before. Accusations might have been levelled at the KGB – or its Russian successor, the FSB – but this was usually in a generic, not specific, sense. Why the change?

It could be, of course, because the UK knows for certain that it was the GRU that targeted the Skripals. But it could equally be that officials simply assumed this because the GRU was Sergei Skripal’s agency, or because the GRU was already in the dock in the US for alleged involvement in hacking. Or it could be because it sounds much scarier than just saying “intelligence”, or even – though I concede this is unlikely – to make clear to Vladimir Putin that we are not blaming him, because the GRU was never “his” agency.

But there is a big contradiction here. On the one hand, the GRU is being presented as a bunch of duffers, whose decorated and highly qualified agents were booked into an east London dive, behaved badly, were deterred by a bit of snow, abysmally failed in their mission, and now face the wrath of Putin. On the other hand, we are told that the GRU is the crème de la crème of state agencies, that Russia is mighty and malevolent and that we should be very, very afraid. Which is it?

Lastly, let’s consider the connections that the UK public is being encouraged to make. Between the two Bellingcat identifications of Chepiga and Mishkin, a clutch of western states, including the UK and the US, came out with a coordinated condemnation of specific cases of Russian cyber-espionage. One related to the chemical weapons watchdog, the OPCW, back in April; another to the World Anti-Doping Agency in Switzerland. All this was presented to the UK public at least in the context of the Skripal case.

But there is a broader and more obvious explanation for Russia’s “behaviour” here – which is that, whether in sport or in matters of chemical weapons, the western allies have closed ranks to exclude Russia from information it is entitled to as a member of these international organisations. In such circumstances, wouldn’t you try to find out what was going on? Might you not also wonder why an apparent attack in an English city was being treated not as a crime – so a police matter – but as “the first use of a chemical weapon in Europe since the Second World War”, which allowed it to be immediately shut behind the impenetrable wall that supposedly protects UK intelligence and state security?

And the point that troubles me. For all the “revelations” of recent days, we are no further forward in knowing what happened to the Skripals – or to Dawn Sturgess, who remains the only person to have died, or to her partner, Charlie Rowley, who has now, like the Skripals and Detective Constable Nick Bailey, disappeared from the media. The two men caught on CCTV in Salisbury may indeed be GRU agents – though why the GRU would squander its brightest and best on such an apparently incompetently executed operation raises doubts. But no UK court would convict them of even attempted killing on the “evidence” that has so far been produced.

The CCTV footage from Salisbury has huge lacunae – though it is established that the cameras were working in Salisbury that day – and does not include any of the pair less than 500m from the Skripals’ house, nor any of the Skripals themselves. Why not? We still do not know where they were for most of that Sunday morning, who they might have met, or for what purpose, or precisely when the presumed attack occurred. Those are huge gaps.

Now, it is also true that Russia’s information machine has hardly covered itself in glory. Its response to at least some of the UK accusations have been weak or in dubious taste, to put it mildly. The RT interview (which was also broadcast on Russian domestic TV) seemed designed to make the Salisbury “tourists” a laughing stock. And Russia has not been as vocal as might perhaps have been expected in demanding consular access to Yulia Skripal, which might seem to cast doubt on its claims of innocence.