For a thumbnail guide to the gravity of the Russian spy crisis, consider this. It has made Boris Johnson look a bit muddled.

Ordinarily, the Foreign Secretary is the safest imaginable pair of diplomatic hands. Whether reciting colonialist, Buddha-ridiculing poetry in the Buddhist temples of Myanmar, or hinting that British nationals wrongly imprisoned there were up to no good in Iran, no one has a more masterly command of his brief.

Yet the attempted murders of Sergei Skripal and his daughter Yulia in Salisbury have left Boris looking bamboozled about how precisely to respond.

He definitely wants Britain to be really tough on Russia, assuming the Kremlin was behind the attacks. We know that because someone or other - though you’d have to be George Smiley to hazard a guess - leaked a snippet from last week’s Cabinet meeting in which hardliner Boris pressed soppy Theresa May to be really tough.

If she abruptly told him to fall silent, as reported, small surprise. Their relationship is directly modelled on the one between The Dude’s bowling friends in The Big Lewbowski. Every time Steve Buscemi’s Donny opens his mouth, John Goodman’s Walter yells “Shut up, Donny, you’re out of your element.”

But is Boris out of his element, for a refreshing change, in identifying this summer’s World Cup as the mode of retaliation? If the Kremlin was behind events in Salisbury, he told MPs, “It is very difficult to imagine how UK representation at the event … could go ahead in the normal way.”

The confusion came when he later claimed the boycott he had in mind concerns officials and dignitaries. Even that’s not a terrible idea. Robbing the opening ceremony of some blazered FA pinheads, or even Prince William, would be a proportionate counterstrike against the export of state-sponsored assassination to the pizza parlours of Wiltshire.

But if Boris’s original idea was to withdraw the England team, as it appeared, he needs to do a U-turn on his U-turn and get back to where he started. Nothing - literally nothing - would alarm Moscow like the notion of a World Cup without England.

If the Government made that threat crystal clear, Putin would cough to the Salisbury business, and promise never to be so naughty again. He understands that losing the country which came so close to taking Iceland to extra time at Euro 2016 wouldn’t just rock world football to its foundations.

It would spark anti-Putin riots on the streets of Vladivostok and Yekaterinberg. A week before the first round of a finely poised presidential election (it’s Vlad vs Some Family Friend Of His Who Doesn’t Look That Keen To Break The Five Per Cent Barrier), he can’t afford that.

Russia may be a riddle wrapped in an enigma within a cloud of mysterious nerve gas, but everyone knows there are three things its people simply will not do without. Vodka. Fur hats in winter. And having their World Cup graced by Dele Alli misplacing a 14in pass to Harry Kane, or Raheem Sterling finding the corner flag with a shot at goal from the edge of the six-yard box.

Small wonder, then, that Labour MP Chris Bryant, chair of the all-party Russia group, advocates a boycott to stop Putin using the World Cup like Hitler used the Berlin Olympics. "Putin loves using these moments to glorify Russia,” he explains. “It will be like 1936 all over again."

Nothing undermines an argument’s strength like citing Hitler as the point of comparison, especially in the context of the Russia that fought Nazi Germany at incomparably greater cost than any other country.

If Bryant makes one error, it is ignoring that Berlin wasn’t the Aryan race propaganda coup of the Fuhrer’s stickiest dreams. Perhaps he doubts there’s a Jesse Owens figure in Gareth Southgate’s squad, which seems cruelly dismissive of such historical sporting titans as Phil Jones and Ryan Bertrand.

Despite that, he’s correct to push for the boycott. The point of principle - that we never placate undemocratic, authoritarian governments that interfere in the affairs of sovereign nations - is reason enough on its own. What’s the point of hammering the Saudis for their war in Yemen by selling them weapons and bowing before their Crown Prince, if we aren’t equally hard on the Russians?

But there are practical considerations as well. Russia expert Edward Lucas told Jeremy Vine on Radio 2 that if England go, the players might have their urine samples doctored to frame them for doping, and be drugged to “slow them down”. One senses Lucas hasn’t been watching the lads closely if he thinks the Russians would bother making them more lethargic. An induced coma couldn’t do that.

As for Boris, he must shake off his own lethargy and force May to threaten the full boycott if that takes his 19th resignation threat since Christmas. And he needs to do it this instant, in good time to sway the Russian presidential election more conclusively than the Kremlin influenced Trump’s.

The Russian people have astonishing powers of endurance, but they would not brook a home World Cup without the goliath that cemented its footballing superpower status in the last one by losing two group games, and holding Costa Rica to a scoreless draw in the third.