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Prince William, Duke of Cambridge, and Catherine, Duchess of Cambridge, in an Alexander McQueen dress she first wore in 2012. Scroll through the gallery for more of the night's best fashion.
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Ella Balinska wears a floral-print dress with a long train by Giambattista Valli Couture.
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Charlize Theron wears a sculpted purple chiffon gown by Dior.
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"Queen & Slim" star Jodie Turner-Smith stunned in a floor-length yellow Gucci gown.
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Greta Gerwig, in Gucci, with her filmmaker partner Noah Baumbach.
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Saoirse Ronan arrives on the BAFTAs red carpet embracing -- like the Duchess of Cambridge and Joaquin Phoenix -- sustainability. Ronan wore a spaghetti strap Gucci gown created with discarded satin textiles.
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Rebel Wilson wears a two-tone sequined dress by Nepalese-American designer Prabal Gurung.
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Al Pacino arrives in all-black Armani.
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Gillian Anderson matched a black dress by Camilla and Marc with a pair of Jimmy Choo shoes.
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Naomi Ackie wears an elegant lime green dress by Valentino.
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Scarlett Johansson in a Versace gown, hand-embroidered with Swarovski crystals. The Italian fashion house said it took 550 hours to create.
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Joaquin Phoenix has promised to wear the same Stella McCartney tuxedo throughout awards season to send a message about sustainability in fashion.
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Daisy Ridley in an asymmetrical design by Oscar de la Renta.
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Renée Zellweger in a lustrous baby-pink gown by Prada.
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Margot Robbie, who was nominated twice in the Best Supporting Actress category, arrives in an elegant Chanel gown.
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Olivia Colman wears an embroidered black silk creponne dress by Alexander McQueen.
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Zazie Beetz wears a burgundy Marina Moscone gown with a high thigh slit.
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Robert De Niro in an Armani suit.
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Florence Pugh wears an extravagant ruffled hot pink dress by Dries Van Noten.
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Zoe Kravitz wowed in a figure-hugging gold Saint Laurent gown, paired with bright red earrings and matching lipstick.
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Best Director nominee Quentin Tarantino in an all-black suit.
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British costume designer Sandy Powell had stars sign her pantsuit, which she reportedly intends to auction off.
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Comedian Aisling Bea arrives in a sequined dress.
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Lily-Rose Depp in a lace Chanel catsuit with dress overlay.
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Best Actor nominee Adam Driver and his wife Joanne Tucker. Driver is wearing a Celine suit.
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Laura Dern wears a velvet Valentino dress embroidered with pearls, feathers and red rhinestones.
CNN  — 

Catherine, Duchess of Cambridge, took a stand for sustainable fashion on Sunday night, rewearing a familiar Alexander McQueen gown to the 73rd annual British Academy Film Awards (BAFTAs).

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Charlize Theron wears a sculpted purple DIor gown

The Duchess had first worn the elegant floor-length white gown, which is embroidered with golden hibiscus flowers, to a state dinner in Malaysia in 2012.

The outfit choice was in keeping with the BAFTAs’ new efforts to prioritize sustainability.

In January, the organizing body announced it would be encouraging guests to opt for more environmentally friendly fashion choices – whether bought from sustainably minded brands, rented or sourced from second-hand retailers – and presented guests with a pamphlet from the London College of Fashion’s Centre of Sustainability to help guide their decisions.

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Zoe Kravitz in a sequined gown by Saint Laurent.

In keeping with that spirit, “Joker” star Joaquin Phoenix wore the same bespoke Stella McCartney tuxedo he vowed to wear for the duration of award season (so far, he’s worn it to the Golden Globes, the Critics’ Choice Awards and the Screen Actor’s Guild Awards); and “Little Women” star and Best Actress nominee Saoirse Ronan wore a simple black Gucci gown crafted from discarded satin textiles.

01:19 - Source: CNN
A brief history of the red carpet

But for the most part, guests (or at least their stylists) prioritized glamour, opting for new designs from the usual heavy hitters that didn’t boast specific green credentials.

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Scarlett Johansson in a custom Versace gown.

Scarlett Johansson (doubly nominated for Best Actress and Best Supporting Actress for her roles in “Marriage Story” and “Jojo Rabbit” respectively) shined in a pink mermaid dress embellished with beading and a train of feathers.

Naomie Harris, in glittering silver Michael Kors, Zoe Kravitz, in gold Saint Laurent, and Emilia Clarke, in Schiaparelli Couture, continued the sparkling theme.

Brightening up the February evening, a number of stars opted for Crayola-bright shades, from Charlize Theron in plunging purple Dior and pregnant Jodie Turner-Smith (star of “Queen & Slim) in yellow sequins, to Laura Dern in nostalgic fuchsia Valentino.

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Adam Driver wearing a Celine suit and his wife Joanne Tucker.

Adding a touch of playfulness to the proceedings, newcomers Florence Pugh (nominated for Best Supporting Actress for her role in “Little Women”) Kaitlyn Dever and Ella Balinska all donned tiers of pink ruffles, reaffirming that, in spite of the pomp and pressure, the red carpet is still the ultimate place to have fun with fashion.