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The bag as armour, the bag as status symbol, the bag as back breaking torment: these we know about. But as of yesterday there is now the bag of biting social satire. Chanel’s quilted classic 2.55, now made to be worn around the ankle and just big enough to contain an alcohol or drugs monitor.

Don’t have a drug or alcohol problem? No worries: this beauty will make the world think you do.

That’s one fashion crisis solved. And not before time. Recent fashion spreads along the uplifting theme of rehab, in which models in various states of mental breakdown and to-die-for wardrobes show a lot of leg (the upside of being dragged by your shiny hair extensions along an institutional looking corridor) have occupied page after page in American Harper’s Bazaar and Italian Vogue. Yet arresting (and arrested) as the models looked, neither magazine offered practical solutions for what to wear to have your stomach pumped or how to tie a straitjacket stylishly.

It takes an arch mischief-maker and observer like Karl Lagerfeld to seize the day. Yet Lagerfeld admits the monitor-bag came about serendipitously. It was the model Rachel Zimmerman, experimenting at her fittings before the show, who tried strapping the dinky purse round her leg. “It looked so elegant,” mused Lagerfeld. “After all, there’s nothing much else going on around the ankle.”

Rehab stars were not the only celebrities referenced. The spirit of American aesthetes, Sara and Gerald Murphy, supposedly the inspiration for the Divers, the golden couple in Scott Fitzgerald’s Tender is the Night, was palpable. In those days the gilded set kept their peccadilloes private, preferring to look demure and primped in spiffy evening gowns that sprouted enormous puffed sleeves or sweet chiffon tea dresses with high necklines and bows. Occasionally one longed to remove a sequined bow from Chanel’s necklines and belts because beneath lay a perfect (and perfectly simple) crepe silk gown with kimono sleeves and an air of 1940s elegant, sensuous authority that didn’t really require further embellishment. But Chanel, in the show at least, is about piling on accessories — from the Sir Walter Raleigh pearl orbs that dangled from the models’ lobes or the Marilyn Manson cut-out black leather elbow length gloves to the recycled denim jackets and jeans (some melded with the label’s signature boucle tweed).

The denim, along with dollar signs and stars and stripes motifs were a political statement of sorts. “Without America, Europe would be fascist or communist,” said Lagerfeld after the show, between fielding questions about puffed sleeves and Fashion Rocks in four languages. “That may not be a popular view right now, but people forget what would have happened in the Second World War without America.” That’s Lohan, Sir Walter and Sarkozy’s foreign policy covered in one show then. And did I mention the crotch-high snakeskin silver boots?

Alexander McQueen dedicated his show not to Americans but to one Englishwoman, his late mentor Isabella Blow. Despite rumours of rifts between him and some of her friends, McQueen was well supported, with Blow’s widower, Detmar, in the audience and Philip Treacy’s hats on the catwalk.

It was, as promised, pure Isabella, with a soundtrack featuring flapping birds’ wings, thunderous hooves, running water (the backdrop to her aristocratic life in Gloustershire) and the contradictory energy of the clothes she always wore — structured carapaces that diminish waists, exaggerate shoulders and hips and should by rights make a woman look powerful and yet somehow often emphasise her fragility.

One model struggled to complete her catwalk odyssey in 10-inch chopin sandals. Another appeared trapped behind metal wires. Others sprouted pyramids of fabric from their hips, inhabiting a space normal clothes wouldn’t provide. Pure fashion: to misquote Wilde, never pure and rarely simple.

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