The question on the minds of a number of prominent Russians is not why Britain has acted precipitously, but why it has taken so long. They are referring not so much to the specifics of the murder of Alexander Litvinenko and the demand for the extradition of Andrei Lugovoi, but to the UK's approach to foreign residents in general. Why, they wonder, have we allowed our capital city to become Londongrad?

The relationship between the Kremlin and London is perhaps the most complex of all, as the new hyper-capitalist Russia seeks to assert itself on the world stage. Few Russians make it over to the US - the visa rules are more stringent. Trade is brisk with the Germans, Italians and the French (who have just snapped up a new energy deal). They may own lavish properties in Portofino and Courchevel; but it is the combination of low tax, big profits, private schools and, until recently, personal safety, that has lured the next generation of Russians to London.

The problem, as Russians are all too keen to acknowledge, is that among the 300,000 now settled in "cloudy Albion" there is a sizeable sprinkling of criminals and spivs. The Moscow of the early 1990s, when Boris Yeltsin and his western advisers allowed a small group effectively to steal an entire nation's natural resources, was a city of stretch limos and shell suits. Many of these types then upped sticks for London, easing themselves into Armani outfits and Knightsbridge town houses. All the while, the British authorities - unlike their counterparts in other western states - asked no questions when issuing visas.

This indulgence is now being used against the British government. Russian officials compare Boris Berezovsky, the exiled tycoon now living under threat of death in the UK, with Abu Hamza and other assorted Islamists of the 1990s. The argument applied about Londonistan - that Britain turned a blind eye to Muslim radicals in the hope of keeping trouble off its streets - is now being applied to Londongrad.

During a brief trip last week to Moscow, which coincided with the tit-for-tat expulsions of four diplomats from each side, I heard the following argument several times: if Britain didn't want polonium poisoning, it shouldn't have let in assorted dodgy former KGB agents in the first place. Litvinenko, Lugovoi, Berezovksy and their like are regarded as birds of a feather.

Britain's hard line is being driven in large part by its ambassador to Moscow, Anthony Brenton. He was flown to London to brief David Miliband on the new Foreign Secretary's first weekend, warning the incoming government of the growing dangers posed by Vladimir Putin. He has argued - and Miliband and Gordon Brown appear to have accepted this - that a signal must be sent that Britain will not tolerate the FSB (the successor to the KGB) assassinating its enemies on UK soil. The British view is that the Litvinenko killing and the recent attempt on Berezovsky's life (the suspected assassin was known to British intelligence, was arrested on 21 June and bundled out of the UK straight after) are just the start.

That is why the Brits decided to take such a tough stance on the Litvinenko affair. They knew that, under the Russian constitution, it would have been impossible to extradite Lugovoi. They also have little reason to doubt that the poisoning was directed from the very top. Far from being a strangely ostentatious form of dispensing with someone, it could have worked well. Had Litvinenko ingested more at the first instance, he would, say officials, have died quickly, and Russia might have got away with it.

Now the British government's aim is to show that there is a real cost attached to such activity, to try to ensure the Russians won't do it again. The British are counting on help from two groups. Support came from the EU and US, but it took a few hours longer than needed to show the Kremlin that the international community put solidarity ahead of trade. Intriguingly, the British are also hoping that Russia's new corporate elite might begin to urge Putin (ever so gently, as they know the consequences of interfering in politics) that a major confrontation with Britain might harm Russia's business army in London.

There is little short-term prospect of a significant improvement. Putin appears intent on standing down as president next year. A number of successors have been mooted. The two favourites are first deputy prime ministers Sergei Ivanov and Dmitry Medvedev. Two others are now gaining favour, Vladimir Yakunin (head of state railways) and Alexander Tkachev (governor of Krasnodar province), who recently helped win the 2014 Winter Olympics for the city of Sochi. To varying degrees, these four come from the same world as Putin. They see how his nationalist-autocratic approach has left him riding high in the polls.

Any notion of liberal democracy will have to wait a while. In the meantime, all the west is hoping for is a little calm on its streets.