He paints a vivid picture of the frantic scramble to get that brave jamboree approved and assembled at a time when everything from bricks to butter was as scarce as orchids in Orkney. But austerity wasn’t the main problem. As with our own dear Millennium Dome, everyone in 1951 had a different notion of what the festival was supposed to be.

Morrison, a populist politician to his fingertips, thought of it as “the people giving themselves a pat on the back” after long years of war and rationing. In truth, he also saw it as his own monument. His main ally, the wily Gerald Barry (editor of the News Chronicle and subsequently the festival’s director), saw it as a showcase for Hugh Casson and his progressive young chums in architecture and the arts.

For its part, the music establishment desperately craved a new concert hall to replace the bombed Queen’s Hall, and rightly saw the festival as a golden opportunity to get one. But they were horrified when Morrison offered some Thames mudflats near his beloved County Hall for the purpose. South London? My dear, the noise, the people! Nostalgists saw the festival as a way of rekindling the imperial glories of the Great Exhibition, 100 years earlier, or at least the grandiose 1924 Empire Exhibition, which had spawned Wembley Stadium. But most of Morrison’s Cabinet colleagues — committed to dismantling the Empire faster than you could say Mahatma Gandhi — desired quite the opposite. For them, the festival was a chance to celebrate their new Welfare State Britain as a kind of born-again Garden of Eden: egalitarian, enlightened and self-sufficient.

So the festival’s supporters were often at loggerheads. But it also had powerful enemies. The Beaverbrook press hated it, mainly because it was seen as the baby of the rival News Chronicle. Churchill hated it — perhaps, as Nicholson suggests, because its exhibitions focused on the future rather than harking back to the valiant years of war.

And, initially at least, many ordinary people deplored spending £12 million on a five-month frivolity at a time when chronic economic crises were delaying the massive reconstruction programmes needed after the war. The satirists gleefully pointed out how appropriate it was that the festival’s most visible landmark was the 300ft-high Skylon. Like Britain in 1951, they quipped, it had no visible means of support.

Yet the festival triumphed. Between May and September 1951, eight million people flocked to the South Bank. What’s more, its Modernist pavilions — a gleaming oasis of light, colour and playfulness in drab, bombed-out London — not only influenced British design for decades but came to symbolise a new national “can-do” spirit.

So what did the festival organisers get so right in 1951 that the perpetrators of the Dome got so wrong in 2000? The usual explanation is that the Dome failed largely because it was perceived as a ludicrously expensive folly whose chief purpose was to disseminate Blairite propaganda.

Yet the 1951 festival was, if anything, an even more blatant exercise in rose-tinted nationalism. Nobody leafing through its catalogue of exhibits today can fail to be startled by its lavish eulogies to the British coal, steel, shipbuilding and motor industries — complacent plaudits apparently devised in astounding ignorance of the problems that would overwhelm each of them within 20 years. Or its myopic assertion that British astronomers, working with earthbound telescopes, would continue to be “the leading explorers of outer space” — a bizarre delusion to propagate at a time when the Russians and Americans were on the verge of putting men into orbit.

No, the 1951 festival carried just as much of a political “agenda” as the Dome would do later (though in 1951 they wouldn’t have used that ghastly word). The difference, I think, was in the mood of the country. Something in the postwar climate triggered a startling cultural renaissance in Britain. Suddenly there was a thirst for intellectual stimulation, for artistic excellence, for new modes of expression, for irreverence and iconoclasm.

So many great arts institutions were born in that heady era: the Edinburgh and Aldeburgh Festivals, the Third Programme, the Royal Opera, National Theatre, Philharmonia and Royal Philharmonic. Radical spirits such as Britten, Tippett, Osborne, Arden, Pinter and Bacon began to kick new creative life into a nation that had been languishing in an cultural backwater. Mass entertainment was transformed by television and then by a surge of youthful energy in pop music and fashion. Future historians, I believe, will judge the quarter-century from 1946 to 1971 to have been a golden age for culture on these isles. And the 1951 festival rode the crest of this wave. “It was the first thing after the war that gave people hope that there could be a different, better Britain,” Nicholson says.

Well, today we certainly have a different Britain: far more prosperous, healthy, socially liberated. But has the fizz gone out of our cultural life? For most people now, the pursuit of happiness largely boils down to shopping and sex, one way or another. Few people really seem to need the arts. Back in 1951 Marghanita Laski had a premonition that the festival, “far from marking a rung on the ladder of progress”, would in fact come to signify “the furthest pinnacle we could reach”. Looking around today, can one say that she was wrong?