It also suggests they were already laying the groundwork for the assassination attempt on Skripal more than a year later. Flight records show one of the assassins - Alexander Mishkin, using the false name Alexander Petrov, flew to the UK at least twice before the Salisbury attack - once in late 2016 and again in March 2017.

Sources have pointed out that if Skripal’s MI6 handler - a senior officer in MI6 - had ever worked for Orbis, he would never have been described as a “senior analyst”. The source said: “That’s a title that is used by 20-somethings just starting out in this kind of work. The agent who recruited Sergei Skripal would never be described as a senior analyst because he is much more experienced than that.

“The chronology is really important because this LinkedIn reference appears a long time before the attempt on Skripal but at a time when Christopher Steele is under scrutiny over the dossier. It’s possible the Russians were already laying a trail on Skripal. They were putting a wedge between Washington and London.”

In the months before Theresa May categorically accused the GRU of carrying out the nerve agent attack in a Commons’ statement, there had been speculation - much of it from the Kremlin - that MI6 had killed Col Skripal.

There were a lot of takers for such a theory at least in the months before the assassins were finally unmasked as Anatoly Chepiga and Alexander Mishkin, two senior GRU men previously awarded Russia’s highest honour by Putin himself. They were identified following a lengthy investigation that included studying hours of CCTV in Salisbury, cross checking with flight manifests, and forensic evidence left at a hotel room where they stayed in London. Intelligence agencies discovered their true identities.

But by then the conspiracy theory had already been seized upon, fuelled by the LinkedIn claim that Skripal’s handler was working for Orbis.

Craig Murray, Britain’s former ambassador to Uzbekistan who quit in protest at the West’s support for the country’s brutal dictator, was one of those leading the charge.

In his own blog posting in April, our former man in Tashkent wrote: “We still have no idea of who attacked Sergei Skripal and why. But the fact that, right from the start, the government blocked the media from mentioning [the MI6 handler], and put out denials that this has anything to do with Christopher Steele and Orbis, including lying that [the handler] had never been connected to Orbis, convinces me that this is the most promising direction in which to look.”

Mr Murray went on: “It never seemed likely to me that the Russians had decided to assassinate an inactive spy who they let out of prison many years ago, over something that happened in Moscow over a decade ago.”