I’VE a confession to make: I don’t know who tried to murder the Russian double-agent Sergei Skripal and his daughter Yulia, nor why, though I’ve a pretty shrewd idea that someone in Moscow does.

But I am not entirely convinced the poisoning was masterminded by Vladimir Putin as part of his current re-election campaign in an attempt to prove “I’m a tough guy, no one messes with me”. I don’t think too many Russians, or others for that matter, need convincing on that score. And anyway, when you ban your main competitor from running against you, and you control virtually all the media, you are unlikely to feel the need to resort to murder to boost your electoral chances.

The Russian connection to the nerve gas attack is pretty clear but not much else is. It makes little sense, I would have thought, for Russia (which is big, very big, in the spying business) to disrupt the system of “spy swaps”. They mean that they can almost guarantee its agents safe return to Russia if caught – though whether a spy in the West would regard that as a threat or a promise is an open question.

What I do know is that in contemporary Russia big business, government, crime and espionage are all highly intertwined – TV viewers saw this with the series McMafia and I witnessed it first hand when I got mixed up with the murdered Russian spy Alexander Litvinenko and his erstwhile “boss”, the also now-deceased Russian oligarch, Boris Berezovsky

When Litvinenko first fled Russia (after denouncing Putin) I was asked to work with him to write his application for asylum, to prove that he was in mortal danger if he was returned to Russia. So we spent a week together in a solicitor’s office in London, or in the words of The Sun at the time, “Litvinenko was... holed up somewhere in the South of England being debriefed by MI6 officers”.

He told me of his life as a “crime-buster” where the worlds of the security services, the Mafia, gangsters and terrorists all collided. This happened most dramatically, he told me, in one particular incident that had grabbed international headlines – the bombing of a block of flats in Moscow which killed 293 people (which Putin blamed on Chechen separatists and gave him the excuse to launch the second, very bloody, Chechen war). Litvinenko claimed that Putin was behind the bombing, but it soon became clear that in the lawless Moscow of 1999 the FSB (the successor body to the KGB), Chechen separatists and Mafia elements, mostly funded by oligarchs, formed ever-changing alliances.

And so, it continued in the London of 2000 where Litvinenko sought asylum. He was sheltered and funded by Berezovsky one of the shadowy oligarchs who met a sticky end, and he spent time, too much time, colluding with MI6, other secret services, Chechen separatists and others, all thriving in what was dubbed Londongrad – a place where we (or at least successive governments) allowed, indeed encouraged, fabulously wealthy Russians, many with very dubious backgrounds, to settle. London property provided a safe and lucrative place to hide their mostly ill-gotten gains. And we turned a blind eye to what was going on.

Following the attempted murder of Skripal the news website Buzzfeed listed 14 people, identified by US spy agencies as being linked to Russia, who had died in mysterious circumstances – and in all cases the UK police had shut down inquiries. And earlier this week a 15th name was added when Russian exile Nikolai Glushkov – a close friend of Litvinenko’s backer Berezovsky – died in mysterious circumstances. It’s worth recalling that Mrs May, as Home Secretary, blocked any public inquiry into the death of Litvinenko for ten years.

We have welcomed the oligarchs, and their money, for crude economic reasons and have allowed them almost free rein. I remember one very wealthy Russian telling me that they regarded London as “our playground... we can get away with almost anything here as long as we keep bringing in the cash”. So now our laissez faire attitude has rebounded on the good citizens of Salisbury, or at least on two of their number. Was Skripal poisoned by Russian stage agencies seeking revenge for his defection or by Russian Mafia elements working on their own behalf or on behalf of some oligarch (the distinction is often unclear)? I do not know, but what I do know is that while there are many decent hard-working Russians living in the UK, we have to recognise that we have opened the playground to the oligarchs and turned a blind eye to their deadly games – perhaps we now need to employ some tougher playground supervisors.

Ivor Gaber is professor of political journalism at the University of Sussex