The belief that the past was better than the present, and the only way forward is back, can be found in the corners of any society at any time. But when nostalgia grows to dominate Britain and much of the west it is as sure a symptom of decay as the stink of dry rot. Every step of Britain’s decline has been accompanied by the sound of sighs for a lost country. To confine myself only to the past few weeks, we had Boris Johnson ordering a new royal yacht “to display the UK’s burgeoning status as a great, independent maritime trading nation”, a £200m attempt to feign 19th-century splendour that covers up the impoverishing consequences of Brexit on the UK’s real trade. After that, we had ministers promoting a well-meant but equally deceitful patriotic song that declared: “We are Britain/ And we have one dream/ To unite all people/ In one great team.” The yearning for a united country would be less pitiable if the same ministers had not partitioned the United Kingdom by putting a trade border down the Irish Sea and were not now driving Scots into the arms of separatists, who are no slouches when it comes to myth-making themselves. The Brexit movement was, above all else, a nostalgic movement. You should have guessed it would end badly when it failed to decide what imaginary past it wished to return to and still shows no sign of settling the matter today. Sometimes, it’s the 1850s, when Britain was a “great, independent maritime trading nation”. Sometimes, it is the 1950s, when we were united in “one great team” before the permissive society ruined everything. Sometimes, it is the summer of 1940, when Britain stood alone against a dangerous continental foe. Modern conservatives are a brothel keeper’s nightmare: they can never identify the fantasy they want to act out. All they know is that they want control, as if Britain were still a great power able to set its own rules rather than a medium-size European country whose influence depends on its alliances. Even now they have control, they cannot say what they want to achieve with it. Many on the left believe conservative nostalgia is a yearning for a white country that existed before mass immigration. I am sure race is part of it but the Pavlovian response that the right is racist makes little sense when the cabinet has so many members from ethnic minorities and the Home Office’s “hostile environment” of checks by police officers, landlords, employers, banks, doctors, hospitals, universities and marriage registrars is about to be turned on white EU citizens who haven’t filled in the required paperwork. I do not mean to minimise the damage it causes when I say, instead, that conservative nostalgia is a desire to feel comfortable before it is anything else. The assault on the National Trust for telling the truth about slavery and colonialism reveals its nature. It could only happen in a society that wants to wallow in the satisfaction of seeing country houses as backdrops for Regency romances rather than as the profits of human bondage. To my mind, the best way of understanding Johnson’s appeal is that he allows his supporters to relax and laugh along with him as he joshes away the realities of our past and present. The Conservatives’ opponents think the prime minister will fall when his supporters see through him. They miss the possibility that a large part of the electorate thinks Johnson’s lies are the best thing about him. If a desire for false comfort sounds relatively benign, I do not mean it to. Political nostalgia is always accompanied by conspiracy theory. Someone, somewhere must have cast the chosen ones out of Eden. The British left is as convinced as the right is of the existence of a lost golden age. In this case, it was postwar Britain before Thatcherism destroyed the authentic Labour world of pit villages, community, honesty, Co-op stores and brass bands. Just as the right sees a liberal, pro-European elite using its “hideous strength”, in the words of Daniel Hannan, its tuppenny Jeremiah, to sabotage traditional England, so the left sees a neoliberal conspiracy destroying solidarity, altruism and community life. The one has Henley Regatta, the other the Durham Miners’ Gala. Both slip into a panic-stricken and paranoid mentality that believes an enemy cabal is extinguishing everything that is worth having. Confident countries are not nostalgic. A self-assured Britain would acknowledge it had a duty to face up to the legacy of slavery and colonialism as modern Germany acknowledged that it had to confront its histories of Nazism and communism. It would take it as read that the present is superior to the past and that, for all our faults, we have progressed enough to admit our mistakes. That a substantial proportion of the British do not believe in progress reveals a neurotic state of perpetual regret that aches to hear the bugle sound the order to retreat. The older you are, the more likely you are to be captured by expurgated memories of the past. The right has built its power by appealing to elderly voters’ outrage at modernity far more successfully than the left has managed to do. When the 2019 British Election Study is published in the autumn, it will report that 61% of over-65s in England and Wales voted Conservative. A little more than irritation at the distortion of the historical record that a greying electorate brings with it is in order. A conservative core vote that has triple-locked state pensions and defined-benefit private pensions did not care overmuch about the destruction of jobs that Brexit would bring because pensioners’ working lives were over and their income guaranteed. Nor do they appear concerned now about the Johnson administration abandoning children after Covid wrecked their education. Their children left education years ago. The ultimate destination of the politics of nostalgia is a state like Vladimir Putin’s Russia, where remorse at the loss of Soviet imperial power and paranoia about western conspiracies sustains a hyper-aggressive and lavishly corrupt dictatorship. The British variant is less dangerous but no less ignorant. It lies to itself rather than to the whole world. It destroys its own country rather than other people’s countries. But, as in Russia so in the UK: nostalgia for a glorious past offers only a failing future. Nick Cohen is an Observer columnist