If the UK wants to increase pressure on Vladimir Putin, it must target those his regime has enriched, that means their money and their ability to travel.

The UK is the preferred playground for the Putin elite, people promoted by the murderous gangster oligarchic kleptocracy. They stash their millions there in fabulous London penthouse flats and Surrey mansions and educate their children in British schools way beyond the means of nearly all British people, Sky News diplomatic editor Dominic Waghorn wrote.

The British visas they have bought by promising to invest more than a million pounds allow them to live with a level of carefree security and freedom they could only dream of in Mother Russia.

And the May government has done little to take that away from them, say its critics.

"Never mind the fact that Russia's intelligence is carrying out chemical weapons attacks in broad daylight on British soil," the author adds.

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After the brazen poisoning in Salisbury in March, the prime minister told the Commons: "We will continue to bring all the capabilities of UK law enforcement to bear against serious criminals and corrupt elites. There is no place for these people - or their money - in our country."

The words gave hope to campaigners who have for years demanded tougher action against such people.

But so far Theresa May's talk of a "full and robust" response has only disappointed.

She could have ordered the use of unexplained wealth orders. They have been used twice in the last year, or so says Transparency International, but not on a single Russian.

Of a total of GBP 4.4 billion worth of foreign money spent on property, a fifth comes from Russia, but campaigners say there is generally little to no investigation into where the money originates.

There are an estimated 40,000 properties owned by anonymous offshore companies in the UK. The government has for some time promised a register of ownership to prevent dodgy people using British property to stash dodgy money.

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They still have not got beyond the draft stage, say observers.

And they complain that the Criminal Finance Act - strengthened in 2017 to toughen up the powers to sanction individuals - has not been used either.

The government says it does remain vigilant for evidence of criminal money being laundered through London and prosecutes where it believes there is evidence.

But that is missing the point. Campaigners and Kremlin critics are arguing for a more rigorous use of existing laws and a sweeping review of their application.

Diplomats have been called in for a talking to. Twenty-three have been expelled.

Economic sanctions remain in place but none of this will worry Vladimir Putin unduly, say Russian analysts.

"If you want to stop Putin, take London and the UK away from his people, one veteran observer of the Russian leader told me back in March," the author wrote.

And while the UK remains a playground for Russia's elite, it will remain the hunting grounds of the spies and assassins doing the bidding of its leader, however chilling the consequences.