Dominating and dictating the style of the Sixties, it was Vreeland who promoted the peerless photography of Richard Avedon and the distinct look of models like Twiggy. Not that this solo show is a humourless catalogue of historical facts for fashion groupies. She was certainly a guru - "Pink," she announced, "is the navy blue of India" - but her style was her own. "The only thing I ever learned was how to dance," she says, and it shows. With a grand manner (and hairstyle) shared by Wallis Simpson, and dressed in basic black lit up by high-rouged cheekbones and a slash of richest red on her lips and nails, Wilson slithers across the set of Vreeland's Park Avenue home like a panther. In the wake of her sudden sacking from Vogue, she fills vases with lilies, prepares for a dinner party, gives great phone, and recounts her thoughts to us. No, not recounts, brays.
Wilson's outrageously entertaining manner has the austerity of Martha Graham, but she hits you like a cross between Katherine Hepburn and Elaine Stritch, with her growling whiplash wit. The beautifully tailored script, by Mark Hampton and Wilson herself, is strewn with drop-dead one-liners, most of them Vreeland's own words. "Excess!", she cries, worshipfully, and indeed lived-in exaggeration is her hallmark. She doesn't like things, she adores them with a quite sublime but ridiculously engaging self-belief. Everything from soft furnishings - "What the hell's the matter with that chair? It looks like Elsa Maxwell" - to Hitler's moustache - "It was just wrong" - lives in the detail.
But she is far less tyrannical than this would suggest. For a start, she is a great believer in vulgarity. "We all need a splash of bad taste... no taste is what I'm against." Wilson's exquisitely timed performance has real comic zest, but it is the unexpected pathos that deepens the pleasure of watching her. As the evening progresses, reality begins to seep through beneath Vreeland's deliciously buoyant confidence. Reading aloud a hostile profile of her in the New York Post, she hears herself speaking the words that she is "in her seventies". Horrorstruck, she hurls the paper across the room.
Like much of this almost guiltily enjoyable evening, the moment is one of high comedy, but, against all the odds, Wilson's superbly unsentimental portrayal is surprisingly touching. In her droll programme note she informs us that, despite her admiration for Vreeland, she had her doubts as "I loathe one-woman shows". She needn't have worried. The role fits her like an evening glove.