It can be a dangerous thing to say that a man is guilty of a murder before he has been tried and found guilty of that crime by a jury in a court of law – as Mr Wopsle found to his cost, in Dickens’s Great Expectations. If you have read that novel you will remember that Mr Wopsle was holding forth in the Three Jolly Bargemen about the guilt of the accused in a recent murder case. Listening to Mr Wopsle’s words was the great London lawyer, Mr Jaggers. In an overwhelming demolition of the unfortunate Wopsle, Jaggers pronounces one of the supreme principles of English jurisprudence. “The law of England supposes every man to be innocent until he is proved – proved – to be guilty.”

That is probably why no British newspapers have pointed out that the first, obvious conclusion to be drawn from President Putin’s refusal to extradite former KGB officer Andrei Lugovoi to the United Kingdom to face trial on a charge of murder is that it amounts to a tacit admission of guilt. Newspapers do not publish what they deem to be defamatory statements even if they are true.

But if the accused will never face a court of law to answer to the charges, what then? Must there be perpetual silence on the question of guilt? That would be to compound the wrong that has been done. It would not be right to the victims. It would not be right to Russia, nor to the people in London poisoned by polonium-210.

Andrei Lugovoi was employed (with others) to assassinate a Russian dissident, naturalized as a British citizen and living peaceably in London. President Putin is well aware of that. He also knows that a finding of guilty against the accused in a British court of law will involve a simultaneous finding in the court of world opinion that the murder of Alexander Litvinenko was ordered by the Russian leadership. This much is only too clear.

Possibly, during court proceedings in the UK, if Lugovoi could ever be brought to trial, his testimony would provide confirmation of one theory of why the murder was committed and at whose instigation, in relation to which a number of facts are already in the public domain. It is now known, from BBC TV, that an 8-page “due diligence” dossier prepared by Alexander Litvinenko was about Victor Ivanov, currently chairman of Aeroflot. It follows, from the hypothesis advanced in a BBC Radio Four programme by Yuri Shvets, that Victor Ivanov is the Mr X described as the "powerful, dangerous and vindictive" individual, "closely associated with President Putin", who may have ordered the murder of Litvinenko. According to the BBC radio programme, when Litvinenko gave the dossier to Lugovoi, in early October 2006, and Lugovoi delivered it (or reported its contents) soon afterwards to Mr X (Ivanov), the decision to assassinate its author was made, in revenge for the termination of a contract worth "dozens of millions of dollars". Perhaps Mr Lugovoi’s evidence would shed light on the truth of this collection of allegations.

It would also be interesting if Titon International, the firm which allegedly employed Litvinenko to carry out the due diligence on Victor Ivanov, would publicly disclose the identity of the British company which commissioned the due diligence report, and subsequently pulled out of the deal.

But this is only one view of why Litvinenko was murdered. There were previous murder victims connected with the 1999 apartment building explosions, about which Litvinenko wrote in his (recently re-issued) 2002 book co-authored with Yuri Felshtinsky, “Blowing Up Russia: Terror From Within”. These include two State Duma deputies: the prominent liberal politician, Sergei Yushenkov, murdered by shooting in April 2003, and Yuri Shchekochikhin, a veteran investigative journalist, poisoned in July 2003, possibly with thallium. The assassination of Alexander Litvinenko, who was hated by the Russian hierarchy as a “traitor” to the organisation formerly known as the KGB, now the FSB, confirms the truth of what he wrote. The testimony of Andrei Lugovoi, supposing he could be persuaded to give it truthfully, would disclose that the FSB under its present head, General Nikolai Patrushev, is a corrupt, totally compromised, criminal organisation, so far beyond a possibility of being cleansed and reformed that it must be considered fit only to be disbanded.

There are only two commonly-held views of the 1999 apartment building explosions which killed more than 300 sleeping Russian citizens, and served as Putin’s pretext for starting the second war in Chechnya: that they were carried out by the Rusian FSB at the behest of the Russian power structures; and that of the Russian authorities, that they were the work of unidentified others for no known motive. The refusal of President Putin to allow Lugovoi to come to the UK to be tried for murder stands as implicit confirmation of the FSB’s guilt, in that it shows the government of the Russian Federation believes that his testimony would incriminate the guilty. And they are nervous.

When Tony Blair had a “frank discussion” with Vladimir Putin about the British government’s demand for Lugovoi’s extradition, earlier this month, Blair may, at last, have begun to understand the truth of the unsavoury character of his enigmatic interlocutor. (To Putin, by contrast, Blair’s lack of understanding of the truth seemed merely obtuse – hence, perhaps, Putin’s comment that British insistence on extradition is “stupid”.) A lawyer himself, Blair may now, as he leaves office, finally and too late have learned, from the refusal to surrender a criminal to justice, one reality of today’s Russia: that it is run by people who are not averse to the commission of crimes when they seem expedient, or convenient, or financially rewarding to members of the siloviki.