“Why all this fuss about Hitler? No-one could be more commonplace. I am told he represents an idea, but I can’t find out what” So smirked Johnny McMullin, Vogue’s ostentatious society commentator, in the 1930s on returning from Berlin.

It’s hard to imagine a 'Vogue'-er response: Hitler’s great crime, according to the Fashion Bible, was his dullness, rather than his fascist 'ideas'. What better, more ridiculous way in which to trample a delusional narcissist, with a penchant for drama than to accuse him of being forgettable? As a black mood settled on Europe, and Britain bristled with anxiety, Vogue just ploughed straight ahead, defiantly frivolous.

The National Portrait Gallery’s massive Vogue 100 exhibition is a history of Britain’s last century, as seen through the glimmering prism of fashion. Since 1916, when it was founded, British Vogue has championed photography. Mario Testino, Patrick Demarchelier, Bruce Weber, Tim Walker, Steve Meisel and Nick Knight jostle on the walls of this crowded exhibition. Walking through the exhibition, you move backwards through the decades. We meet Lee Miller, David Bailey, Irving Penn, Lord Snowdon and the man who bequeathed Vogue its photographic soul, Cecil Beaton.

We watch as styles give way: the lurid colours of the 00s fades to the grungy 90s shoots; we’re shown the glam 1980s, rebellious 70s, swinging 60s and so on, right to the start of the 20th century, as the magazine forged its identity.

There’s some remarkable artistry on display, as we trace the medium of fashion photography back to its foundation: no-one can deny this. But, more than the photographs, more even that the clothes, it is the clamouring, kaleidoscopic cast of characters that gives this exhibition its racing pulse.

We have all the familiar faces, of course. The late Lee ‘Alexander’ McQueen’s portrait resides in an enormous arch; saint-like, over the show. Present day Instagram natives Edie Campbell and Cara Delevingne give way to the Supers of the 90s, then to Grace Coddington, Twiggy and Jean Shrimpton.

But what about their ‘20s and ‘30s counterparts? Ever heard of the glorious the American beauty Mona Bismark, dragging five smitten husbands in her wake. What about Helen Wills Moody, the tennis champion who epitomised sporting chic and from 1927-33 never dropped a Wimbledon set. Or the Queen of the 1930s Parisian jet set, Toto Koopman, whose bisexuality and boisterous bedchamber had Europe aflutter?

Bright Young Things. Couture. Storytelling. Vogue’s absurdity and its frivolity are out in force at this exhibition. And what powerful energies they are. Through the darkest periods of twentieth-century history Vogue’s razzle-dazzle glamour refuses to be dimmed by disaster. “If you have not lost money, then pretend you have,” the magazine preached just after the Wall Street Crash: it made being broke fashionable. Speaking in the Thatcher-ravaged 1980s, Vogue veteran Norman Parkinson said “it’s been so depressing, People want style. They need romance. They need beautiful women in beautiful and provocative surroundings."

Vogue is, and always has been, safely situated in Fantasyland. It’s not clothes the magazine is selling, but escapism - a feathered, ridiculous daydream, that takes people out of their heads for an hour a month. This exhibition is pure frivolity; utter nonsense: and all the better for it.