London CNN  — 

The Duchess of Sussex made an appearance Saturday evening ahead of her second wedding reception in a bespoke gown designed by Stella McCartney.

Meghan and her new husband, Prince Harry, left Windsor Castle shortly after 7 p.m. (2 p.m. ET) in a silver-blue Jaguar E-Type driven by the prince. The car’s number plate bore the date of the wedding: E190518.

The couple were on their way to the private evening reception, hosted by the groom’s father, Prince Charles, at Frogmore House.

Harry had also changed his outfit, appearing in traditional black tie rather than the military dress he wore for the ceremony.

Meghan’s lily white gown featured a high neck and is made of silk crepe. She paired the dress with silky satin heels by Aquazzura, a luxury Italian shoe label. They feature a nude mesh with baby blue soles. Her hair was styled for the second reception by George Northwood, a London-based stylist.

She wore an emerald-cut aquamarine ring that once belonged to Harry’s mother, the late Diana, Princess of Wales.

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The Duke and Duchess of Sussex wave as they leave Windsor Castle after their wedding to attend an evening reception at Frogmore House. The Duchess wore a ring that once belonged to Harry's mother, the late Diana, Princess of Wales.

Meghan’s mother, Doria Ragland, also changed into a Stella McCartney look Saturday evening. She opted for a scarlet red long-sleeve dress in silk cady, paired with a gold box clutch by the same designer.

Around 200 close family and friends received invitations to Frogmore House for the event, another royal residence in Windsor.

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Meghan and Prince Harry set off for Frogmore House.

The royal bride surprised onlookers earlier in the day when she revealed a couture design by Givenchy’s artistic director Clare Waight Keller. Waight Keller was hardly mentioned by bookies and fashion experts in the lead-up to the big day.

Meghan planned to make a speech at the evening event, Kensington Palace told CNN’s Max Foster earlier Saturday.

Traditionally, it is unusual for the bride to deliver a speech at her wedding reception, that honor usually being reserved for the bridegroom, best man and father of the bride.

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After months of feverish speculation, all has been revealed: Meghan Markle, now known as the Duchess of Sussex, chose a dress by Givenchy's Clare Waight Keller to marry Prince Harry.
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The long-sleeved haute couture gown with a simple bodice featured a graphic open bateau neckline that delicately framed her shoulders.
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The silk tulle veil measured 16.4 feet.
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The veil was hand-embroidered with flowers, representing the flora of each of the 53 countries of the Commonwealth.
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Those working on the dress spent hundreds of hours meticulously sewing. They washed their hands every thirty minutes to keep the tulle and threads pristine, according to a statement from the palace.
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Here, a glimpse of the jewelery -- earrings and bracelet made by Cartier.
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The veil is held in place by Queen Mary's diamond bandeau tiara, on loan from the Queen. Crafted in 1932, the diamond bandeau features a center brooch dating from 1893.
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Clare Waight Keller is the first female artistic director of the French fashion house, and a fitting choice for Meghan, who identifies as a feminist.
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At her previous post as creative director of fashion house Chloé, Waight Keller championed a free-spirited, feminine aesthetic that prioritized soft colors. At Givenchy, she's taken a darker, more cinematic turn -- a nod to Tisci's particularly Gothic legacy.

Stella McCartney, the 46-year-old daughter of Paul McCartney, is one of the most renowned and respected female designers in the notoriously male-dominated world of luxury womenswear. Her clothes, which combine elements of traditional femininity with Savile Row-quality tailoring in her designs, have been worn by the likes of Rihanna, Cara Delevingne and Gwyneth Paltrow.

“I’m so proud and honored to have been chosen by the Duchess of Sussex to make her evening gown and represent British design. It had truly been one of the most humbling moments of my career and I am so proud of all the team on this stunning royal day,” McCartney said in a statement.

A number of other guests at Saturday’s ceremony arrived wearing Stella McCartney creations. Oprah Winfrey wore a blush, double-tiered dress with lace trim made of sustainable viscose by the female designer, while Amal Clooney stunned onlookers in a Stella McCartney golden yellow dress.

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Amal Clooney wore Stella McCartney as she arrived with husband George Clooney for the wedding ceremony Saturday morning.

Since founding her eponymous label in 2001, following a term as creative director of Parisian fashion house Chloé, McCartney has been a advocate for sustainable fashion. She rejects the use of fur and leather, and has been vocal in denouncing the environmental damage caused by the fashion industry.

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The number plate on the E-Type Jaguar the couple used to drive to their evening reception bore the date of the wedding.

“It’s just the way I was brought up,” McCartney told CNN in 2015, when asked about her environmental advocacy. “It’s been ingrained in me to have respect for fellow creatures and to be mindful of how one approaches life, so it was a no-brainer for me to take that into the way that I conduct myself in business.”

It’s a point of view that may have resonated with Markle. She and Prince Harry requested that, in lieu of gifts, well-wishers donate to seven charities, including two environmental groups: Surfers Against Sewage and The Wilderness Foundation UK.