It was well done, in the end; in parts, beautifully done. In an era of anniversaries, there was never a chance that the 75th anniversary of the D-day landings could go by uncelebrated. But there were huge risks. Would the events feel like being locked in a glorious, vanished past? How not to appear extravagantly triumphalist or tip into schmaltz? How not to reawaken the stereotypes of the bad Germans?

But the organisers got it pretty much right. The evocation of the day’s events – from paratroopers to the reenactment of cliff scaling – spoke for themselves. The speeches honouring peace and international co-operation were powerful and dignified, against a backdrop of veterans stressing “never again”. As these near the end of their lives, it was perhaps the last chance to bring their past to life, with personal testimonies of a bravery made to seem everyday. Even Donald Trump rose somewhat to the occasion, speaking to the common theme.

However, the truth that hung in the air over the famous beaches, at least for many Britons, was the disjunction between these values and those of Brexit. It betrayed, as at least one veteran gently chided, what they had fought for. I am a baby boomer, the son of a former artillery captain who landed at Arromanches two days after D-day. I got used to him, frustrated in some traffic jam, shouting at the car ahead: “Get a move on, don’t you know there is a war on?”

But when he took his family on holidays in 1960s Europe, he sought out any German his own age with a handshake; if this man was a former soldier, he insisted on buying him a drink. My brother and I would be told to play with his children while Dad tried, in whatever language he could, to say how much he respected his former adversary, how there must never be another war and how we must build Europe together around shared values and interests to prevent it.

We accepted it as another of my father’s irritating idiosyncrasies and were glad to get back on our way, but, looking back, I realise what a profound impact it made. My father shaking hands with a former enemy soldier he had never met before? Live your politics and values if you want to make a difference.

‘Tory leader hopeful Dominic Raab proposes a suspension of parliament this autumn to deliver a no-deal Brexit.’ Photograph: Jeff Overs/BBC/PA

There was a particular moment that he talked about more than once. He had temporarily been put in charge of a prisoner-of-war camp of German tank crews after the battle for Caen. The very young men the other side of the barbed wire, he said, looked indistinguishable from his own men. They weren’t Nazis. They were Europeans caught up in the same terrible events as he was, but unlucky to be born in the wrong country. Never, never again. Europeans had been fighting each other too often. Were our arguments and differences so deep that there was no other solution than killing each other on such a scale? It had to stop. The members of the wartime generation, what the US journalist Tom Brokaw called “the Greatest Generation” in his book chronicling their experiences, were unique. Nobody escaped the dreadful pall of the 1930s depression and the fear of unemployment. Having lived through the privations of a capitalist system that palpably did not work, they found themselves locked in a world war against fascism. It seemed that the good life would never come their way. For them, it was about belt-tightening, facing any hardship, pulling together and, ultimately, coming through.

The searing experience incubated a collective purpose: to build so that it could never happen again. Their legacy – the mixed economy, the welfare state, European and global institutions designed to promote trade, collaboration, peace and help for developing countries – has been resilient enough to offer my generation what they did not have.

Above all, the D-day celebrations signify a shared purpose now lost. What was so painfully won is being put insouciantly to one side, from crucial values to the tools of economic management, and a society absent of an overriding shared purpose is unable to muster resistance. Contemporary capitalism, left too much to its own devices by the rightwing proposition that the state must keep out of the economy, does not work. The inequalities it has thrown up are, as in the 1930s, provoking powerful societal protests. And, as in the 1930s, a new wave of demagogues, of whom Nigel Farage is a prime example, is blaming an out-of-touch elite for misgoverning a population needy of change.

Foreigners must lie at the root of our ills and there is no greater or more intrusive foreign agent than the European Union. Vote Brexit – it offers a purpose otherwise lacking.

Benito Mussolini and Adolf Hitler in Florence, Italy, 1940. Photograph: Alamy

Incredibly, there are even British rightwing politicians using exactly the same language as Hitler and Mussolini. For both dictators, the popular will, expressed in referendums manipulated to produce the right result, had to override parliaments and democratic assemblies, which must be suspended or prorogued if they oppose it. Yet Tory leader hopeful Dominic Raab, deranged by the religion of Brexit, proposes just such a suspension of parliament this autumn to deliver a no-deal Brexit. It is crazed and totalitarian in its spirit, the antithesis of what the millions, including my father, fought for 75 years ago. The feebleness of the reaction – no such man should ever be entrusted with the prime ministership of Britain or even a position in its government – betokens how far we have sunk.

I can write my columns for as long as you are willing to read them, but words do not have the same impact as lived experience. The wartime generation were so shaped by what they lived through that they created the institutions that have served us so well. Maybe the British will have to live through a suspended parliament and the mayhem of a no-deal Brexit to learn that the ultra-populist right, with all its hatred of the other and of international collaboration, offers no worthwhile answer.

Rather, our purpose lies in rebuilding the values and institutions bequeathed to us by that wartime generation. If the D-day celebrations made any contribution to promoting again a collective way of thinking, they will have been worth their weight in gold.

• Will Hutton is an Observer columnist