LONDON – “‘Who ever heard of Moscow Rules in the middle of bloody Hampstead anyway?’ Strickland asked, waving out the match.

‘Bloody Hampstead is right,’ Smiley said quietly.”

In the long history of Moscow-ordered assassinations of Russian defectors on British soil, perhaps the most famous one never happened in real life. It takes place at the beginning of “Smiley’s People,” the final book in John le Carré’s monumental “Karla Trilogy.”

<< Russian Ex-spy and Daughter Poisoned by Nerve Agent, U.K. Police Say >>

Four decades after it was published – and long after the anti-Americanism of the Cold War’s master storyteller had rendered his literary output turgid – on northwest London’s Hampstead Heath you can still retrace the last steps of General Vladimir as he makes his way to a safe house, only to be waylaid among the trees by Moscow Centre’s assassins, who obliterate his face with a soft-nosed bullet. But the general was also playing by Moscow Rules and, moments before he died, managed to hide in the branches a packet of Gauloises, containing the proof that will be found by George Smiley and ultimately bring about the downfall of Moscow’s spy chief, Karla.

Read the “Karla Trilogy” if you haven’t. If you have, read it again. It is still fresh and sparkling, and the literary world is awaiting an heir to Le Carré who can bring alive this latest age of secret warfare between Moscow Centre and the West.

The Soviet Union may have been replaced by the Russian Federation, and instead of soft-nosed bullets defectors are being taken out by mysterious radioactive substances – but it remains Moscow Rules.

On Sunday afternoon, in the pastoral cathedral city of Salisbury, southwest England, a 66-year-old man and his 33-year-old daughter collapsed on a bench not far from the Italian restaurant where they just eaten lunch. Taken to a nearby hospital, they remain in critical condition.

The substance that is believed to have rendered them catatonic – also causing minor symptoms to at least one of the medical personnel who initially treated them – is currently being analyzed at Britain’s chemical-weapons research center in Porton Down, 11 kilometers (7 miles) from Salisbury.

This being Britain, everything is being done by the book and the authorities are being very careful at this point not to blame Russia.

The casualties are Sergei and his daughter Yulia Skripal. Mr. Skripal was until 1999 a colonel in GRU, Russia’s military intelligence branch, and later worked at the Foreign Ministry in Moscow. He was arrested and convicted of treason – for working as a double agent for Britain’s MI6 – in 2004, and released in 2010 as part of a spy exchange with the United States.

Skripal’s wife died of cancer in Britain in 2012, his son, 43, died during a visit to St Petersburg last year, and now the father and his daughter are dying. No reason to suspect that Russia is once again visiting retribution on its traitors, then.

London and the surrounding counties have been the scene of assassinations of Soviet and Russian defectors, dissidents and rogue oligarchs since the 1920s. Similar killings have of course taken place around the globe, but Britain has had a disproportionate number due to the fact its intelligence services were historically on the forefront of the secret war with the Communist International – which long saw Britain as fertile ground for the next great Bolshevik revolution.

London, and the historic universities of Oxford and particularly Cambridge, were great playgrounds where the battle was always fought by Moscow Rules. But the reason for the many assassinations is not just historical: At many periods it has also been due to the political and diplomatic reluctance of many British governments to match the professionalism and determination of their intelligence services with appropriate sanctions following acts of murder on their soil.

Despite the clear involvement of Russian operatives with links to the Kremlin in the 2006 death by poisoning of former KGB and FSB officer Alexander Litvinenko, the British government refused to conduct a public inquiry or demand any formal explanations from Russia.

Litvinenko was poisoned using polonium – a radioactive substance produced in nuclear reactors and not available to regular assassins on the open market.

Britain also preferred not to delve too deeply into other cases in which oligarchs with information on the dealings of Russia’s leadership died mysteriously on its territory, as in the cases of Boris Berezovsky in 2013 and Alexander Perepilichny in 2012. Britain’s diminished international stature and the City of London’s addiction to the billions deposited in its banks by post-Soviet oligarchs have had a dampening effect.

On Tuesday, in the furor surrounding the latest poisoning, British Foreign Secretary Boris Johnson initially said in response to a parliamentary question: “Thinking ahead to the World Cup this July [to be played in Russia, starting in June], I think it would be very difficult to see how U.K. representation at that event could go ahead in the normal way. We would certainly have to consider that.”

An hour later, his office was making clear that under no circumstances was the foreign secretary hinting that England’s soccer team would be boycotting the World Cup, only perhaps at some “dignitaries and officials” staying away.

Interestingly, there is another country where a large number of Russians on the run routinely take shelter.

“No Russian oligarch or dissident has even been assassinated in Israel,” says a former Israeli official. “No one will ever confirm there is a formal agreement, but everyone understands that Israel is a safe neutral zone when it comes to the Russians and Ukrainians.”

That’s why during periods of tension – such as Kiev’s Maidan Revolution in 2014 – many of the businesspeople and officials with interests on either side of the pro-Ukrainian or pro-Russian side migrate for the duration to Tel Aviv, their business jets lining the taxiways of Ben-Gurion Airport.

“The lobby of the David Intercontinental was like a scene from [the movie] ‘Casablanca,’” recalls one Russian-Israeli. “With people from either side sitting together, doing business, feeling safe. That’s what it’s like when the Russians and Israelis share mutual respect and know better than to fuck around and kill people in each other’s backyard.”