If Theresa May expels Russian diplomats from the UK, Vladimir Putin can expel British diplomats from Russia. If we seize Russian state assets, Russia can seize ours.  When we revoke an invitation to Russia’s Foreign Minister, he can point out he hasn’t accepted it.  When Prince Harry and Matt Hancock and Tracey Crouch boycott the World Cup, Russia can live with their absence – as they would be able to live with the unlikely event of the England football team withdrawing from the competition.  The gap would be filled.  The World Cup would go on.  The kudos that Putin will gain from hosting it would scarcely be dented.  If we shut down Russia Today in Britain, Russia can shut down the BBC, if it wants to, in Russia.

For sure, the Prime Minister has stirred up a diplomatic wasp’s nest for Russia.  Donald Trump has come into line.  Emmanuel Macron will doubtless do so later today.  (France’s Ambassador at the UN yesterday took a more robust position than his spokesman.)  But we must presume that Putin game-planned the response which has met Russia in the wake of its dismissive response to the attempted murders in Salisbury.  For although international sanctions are damaging his country, it is unlikely that they will be intensified significantly.

All considered, there is only one significant respect in which the UK has an advantage over Russia in this exchange of diplomatic tit for tat.  Rich Russians are attracted to life in London.  But the reverse does not apply.  Wealthy Brits are not straining to settle in Moscow.  Theresa May was careful yesterday to say that the Government has “no disagreement with the people of Russia”, and Britain shouldn’t become hostile space for Russians simply because of their nationality.  But some of Putin’s friends enjoy sampling the capital’s Michelin-starred restaurants, their wives and mistresses are in and out of Harvey Nicols, and their children are making the most of what Britain’s private schools have to offer – amidst Vaughan Williams countryside which makes for pleasant weekends away.

It’s time bring the curtain down on the show, and May looks ready to do so.  In due course, Putin may come to calculate that the game of denying a Russian connection to the Salisbury outrage (at best) and directly commissioning the use of a chemical weapon on British soil (at worst) isn’t worth the candle.  And relations may thaw.  But it will not be glad confident morning gain.  As we keep pointing out, the Government’s recent verdict is that Russia is now a bigger threat to our security than Islamist or other terrorism.

Welcome to a new Cold War.  It comes with a cost – in defence and security spending, in lost trade and investment opportunities, in foreign policy co-operation over, say, Afghanistan and Iran.  And, to be sure, Russia is pouring money into its armed forces and cyber capacity.  None the less, it is in no better a position to afford to do so than the former Soviet Union.  On corruption, fragility, innovation, human capital, creditworthiness, GDP per head – all the measures that count for most – Russia is, to put it politely, not in a great place.  If Putin has settled on busying giddy minds with a foreign quarrel, both before what passes in his country for free elections and presumably after, one can understand his reasoning.