The dresses the Oscars would NEVER allow: How Margot Robbie and Florence Pugh ditched elegant gowns for more risqué frocks as they let their hair down at after-party... but it's the dry cleaners who are the real winners!

After months of facials, fittings, juice cleanses, make-up mishaps, hair prep, ramped-up Ozempic jabs and heated debates with stressed-out stylists, you might imagine that when the curtain fell on Sunday night, guests at the 96th Academy Awards ceremony would have grabbed their goody bags and left, happy to collapse in a heap on their beds.

That, though, would have been a missed opportunity.

For it's at the after-parties that the stars get a chance to shine with a different type of lustre than that required on the Oscars red carpet. And, this year, it was more obvious than ever.

To be successful, Oscar appearances require a very specific dress code — one that is respectful of Hollywood traditions. Gowns tend to be long, elegant and classic, embellished with embroidery, beading and sequins. Rarely are the fabrics simple prints: that would be deemed too 'daytime'.

For men, the classic black tuxedo is the go-to look.

Emily Blunt in a soft peach lace Dolce & Gabbana gown at the Oscars ceremony on Sunday night

Andrea Riseborough attends the 96th Annual Academy Awards on March 10

Which is why, for many guests, the after-parties are so enjoyable — and not just because of the free bar. Much as a bride might change from her wedding dress into an outfit more suitable for dancing at the reception, so Hollywood's A-list sheds its glamorous skin and slips into something more comfortable. Or, if not more comfortable, then certainly something more experimental and eye-catching.

Of all the post-show events, the Vanity Fair Oscar Party is by far the hottest ticket, and never more so than this year, when it was celebrating its 30th year.

Billed by the magazine as 'the city's most opulent, decadent, impossible-to-crash soiree — a fantasy canteen of Hollywood's megawatt stars smashed against each other at a bar', it offered the perfect chance for guests to flex their fashion muscles.

No matter that they were exhausted: while there was breath left in their bodies, they partied on — invariably in dresses that the Oscars wouldn't countenance.

Leading the charge was Margot Robbie in a beaded gold Thierry Mugler corset that would have been panned on the red carpet, with inevitable cries of 'Where's your skirt?'

No Barbie pink! Margot Robbie in Versace at the Oscars and a gold corset dress by Thierry Mugler at the Vanity Fair bash

Two looks: Florence Pugh, elegant in Del Core, changes into a racier outfit by Simone Rocha x Jean Paul Gaultier for the after-party

Making waves: Lupita Nyong'o — in Armani Prive gowns — topped her later appearance with halo-like hair

Worn with a brown satin shawl, the look, which hailed from Mugler's Spring/Summer 1996 collection, was perfect for Vanity Fair.

By contrast, Robbie's Oscar look was a long, black, sequin column dress by Versace — a rather more sober choice than expected, since she has spent the duration of her promotional activities for Barbie wearing variations of pink, all created by different top designers in homage to her character.

Sheer is a divisive trend that can be hit or miss on the red carpet: it tends to come into its own after dark, when any reveals are rendered less revealing. 

Having chosen an elegant silver gown by Christian Dior haute couture for the Oscars, Charlize Theron changed into a sheer black gown, also by Dior, with a more casual halterneck bodice and a transparent skirt. 

Florence Pugh has long been a fan of sheer, but wisely avoided it at the Oscars. She also chose not to wear her usual Valentino — despite being the face of the brand — opting instead for a silver gown with a satin skirt and crystal embellished bodice by the lesser-known label Del Core.

A daring dresser, she still couldn't resist incorporating a 'talking point' — this time in the form of straps that appeared to float above her shoulders.

By evening, Florence was back on her mission to free the nipple, in a sheer cream dress with strategically placed embroidery over the bustline, by Simone Rocha x Jean Paul Gaultier.

Emma Stone is another fan of sheer. As a brand ambassador for the house, it was a given that the Oscar-winning actress would be dressed in Louis Vuitton for the ceremony and, bar an on-stage zip malfunction, her pale mint green gown with its exaggerated peplum waist was pitch perfect.

For the Vanity Fair party, she wore a less streamlined Vuitton gown that twinkled with silver embellishment, through which her bra was subtly visible. While its asymmetric hem might have jarred at the Oscars, it worked well for a post-award celebration.

Winning outfits: Emma Stone in Louis Vuitton on the red carpet and at the Vanity Fair party

Striking: Anya Taylor-Joy went from demure in Christian Dior to daring — with hair to match — in label Miss Sohee

Too casual? Jennifer Lawrence in polka-dot Christian Dior for the awards ceremony and, later on, glamorous in Givenchy

From satin to sheer: Charlize Theron doubles up in Dior

But there were myriad other ways to stand out than by wearing sheer. After opting for a demure powder-blue, feather-trimmed gown by Armani Prive at the Oscars, the actress Lupita Nyong'o looked ready to party in a halterneck sequin column dress, also by Armani Prive.

Even her hair looked joyful, raised into halo-like sculptural coils. Anya Taylor-Joy was another attendee whose hair was a talking point. At the Oscars, her Christian Dior corset dress was styled with a simple, middle parting that didn't compete with the gown's complex fishscale embroidery.

At the Vanity Fair after-party, her hair became the focus, courtesy of a jewel-encrusted headpiece worn with a black scoop-front mini dress by South Korean couture brand Miss Sohee.

For some, however, the after-party seemed more an occasion to sober up than dress down.

Emily Blunt's soft peach lace Dolce & Gabbana gown was a far more traditional choice than the Schiaparelli gown she wore to the Oscars. With beading at the crotch in the unmistakeable shape of a pair of Y-fronts, the gown might have embodied Schiaparelli's long affinity with surrealism, but some fashion-watchers thought it a joke too far for the Academy Awards.

Jennifer Lawrence was another guest whom many opined got her dress codes mixed up, with her polka-dot Christian Dior gown too casual for the red carpet.

By contrast, her white floral embroidered Givenchy gown was a subtle, delicate choice for an after-party, its train surely destined to be stood upon by revellers three champagnes to the wind. Perhaps, like everyone else, Lawrence was too merry to care.

One thing is for sure: the real winners in Hollywood today will be the dry cleaners.