The farmer swings his scythe, the mushroom pickers scour the woods. This Bruegelian scene is completed by the artists Gilbert & George gathering used laughing-gas canisters from the gutters of Whitechapel. I once spent a happy morning with the pair foraging for these clubbers’ castoffs. Gilbert Prousch, who was born in South Tyrol, and his English partner, George Passmore, featured torpedoes of nitrous oxide in a series of works called Scapegoating (2014). They have been collaborating since the late 1960s and refer to themselves as ‘living sculptures’. They invariably appear in their own art, turned out in ties and tweeds like dummies in a 1950s Burton’s shop window. Their works consist of panels of recurring motifs, each with slight variations, accompanied by sensational tags or four-letter words. Their subject matters are often sexual, scatological or both.

Not everyone’s a fan. The critic Robert Hughes compared the art of the late 20th century to ‘a swollen duff of mediocrity’; he didn’t include Gilbert & George among the few appetising ‘raisins bedded, very far apart’. But if one of the purposes of art is to show us how we live now, Gilbert & George deserve some credit. After all, they were responding to nitrous oxide, or ‘hippy crack’, a decade before MPs got around to banning possession of it. They also remind us of the pungent realities of our own bodies. There’s an academic paper, or perhaps a bawdy TikTok, to be produced on how the art of scrawlings on toilet doors – bums, willies, bad language – has entered respectable galleries on their watch. Their use of blunt, emotive text could be seen as an example of the tabloidisation of the culture.

Gilbert & George are unimaginable away from their beloved East End, like a harmless version of the Kray twins. But they have made forays onto foreign turf, including Russia and China, thanks to the indefatigable James Birch, an art dealer who has written a very entertaining account of their travels, with the help of Michael Hodges, a journalist of many parts. The Whitechapel two found themselves following in the footsteps of such pioneers as Richard Brompton, an 18th-century English painter who was sprung from debtor’s jail by Catherine the Great and repaid her by working on portraits of her and her grandchildren in St Petersburg.

Birch planned a Gilbert & George exhibition in Moscow in 1990, when the Soviet Union was entering its dying days. It was an unlikely enterprise and Birch’s prospects of success seemed slim. The odd couple of British art were great fans of Margaret Thatcher, prime minister at the time. They lost no opportunity to complain about the ‘Marxists’ overseeing culture in the UK, to the bemusement of the arts bigwigs whom they eventually met in Moscow, who were under the impression that they were the ones living in a Marxist state. The late George Melly branded the pair ‘fascists’, not a very helpful contribution from Birch’s point of view and an accusation he firmly rejects. There are even allegations that the British Council was putting the mockers on the plan in the background. How would the homoerotic imagery in Gilbert & George’s stuff go down in far from gay-friendly Russia? As it happened, the British Council needn’t have worried on that score. One Muscovite studied their piece Coming, featuring the two men squinting into the sky at a blizzard of Y-fronts, and decided that it was a sympathetic depiction of the constant assault his country faced from the West.

If Ealing comedies ever come back, Birch’s book would provide a perfect script, with our author as a well-meaning Englishman who mixes with an assortment of tricky customers and, against all odds, is swept towards triumph on a tide of alcohol and luck. The dramatis personae include Birch’s moody, pouting Russian girlfriend, who may or may not be harbouring a secret, a rival London dealer who wants a piece of the action, and a mercurial fixer from Moscow who has mysteriously come into funds after helping to organise an exhibition of paintings by Francis Bacon (the subject of a previous book by Birch and Hodges). A picture donated by Bacon to a prestigious museum may or may not have gone astray.

This book should lay to rest once and for all the idea that Gilbert & George are puerile and solipsistic. This turns out to be not an idea at all but an inescapable fact. Birch recounts a conversation with the artists about the chaos threatening the Soviet bloc: ‘Rather typically of Gilbert & George, they didn’t think about the immediate fate of the 290,000,000 citizens of the USSR. “You don’t think it’s going to affect the show, do you Sergei?” said George.’ During talks about an exhibition in Beijing with a Mr Wang from the Chinese embassy in London, the pair doubled up at every mention of his name, which they gleefully repeated. Despite this, the Chinese were keen on the idea. They liked the artists’ work because ‘the colours are strong’. Birch worried that the mooted show in Beijing was to be part of an exercise in reputation-cleansing for their hosts following the Tiananmen Square massacre. ‘Was I at some level complicit?’ he asks. But it went ahead anyway and even transferred to Shanghai. Notwithstanding the indifference of British diplomats and the heavy-handedness of the People’s Liberation Army, who were entrusted with the hang, it was a great success. Gilbert & George, cannier than they let on, had the catalogues printed by the Chinese. They saved a fortune and sold a great many copies. A reporter asked them the meaning of art. Gilbert answered, ‘Art is everything and art is nothing’, which prompts Birch to reflect, ‘Gilbert’s declaration was, in retrospect, something I felt was true. I could see the bigness and nothingness of their work.’

Their oeuvre is art’s whoopee cushion, which is by no means a bad thing, although some may feel they’ve delighted us long enough with their raspberries. But this rollicking travelogue, a kind of ‘Backside in the USSR’, deserves to be met with a fanfare of trumpets.