When actress Nicola Coughlan joined the cast of Shondaland’s period costume drama Bridgerton as the young socialite and secret gossip pamphleteer Penelope Featherington, hair and makeup artist Marc Pilcher informed her that the creative brief they had for her character was only one word: “dowdy”.

Penelope, the demure youngest daughter of domineering matriarch Lady Portia Featherington, was to be done up in garish pastel dresses and gaudy jewellery, with a hairdo clogged with curls – none of it particularly flattering.

“For the first two seasons, the objective, in the nicest way, was not meant to make me look nice,” Coughlan said in a recent interview.

“A lot of the Featherington aesthetic was a ‘more is more’ approach.”

A supporting player through the show’s first two seasons, Penelope is the main character of the third season, which begins streaming May 16 on Netflix. And as she has moved into the spotlight, her entire style has been altered: a transformation that fans of the show refer to as the “Bridgerton glow-up”.

Gone are the canary-yellow gowns and tacky headpieces. She’s now wearing milder colours and less ostentatious jewellery, and her hairstyles are looser and more elegant.

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In short, she is no longer dowdy.

“At the first fitting for season three, I got teary-eyed,” Coughlan said. “It felt like a ‘Pretty Woman’ moment. They were finally going to let me shine.”

This kind of stylistic reinvention has become common practice on a series known for rotating actors in and out of its sweeping ensemble, and adapting their appearances accordingly.

“When the transition is made from side character to leading character, we think a lot about what story it is we’re trying to tell,” showrunner and executive producer Jess Brownell explained.

When it comes to styling, she said, “It’s a lot more heady when it comes to the main characters.”

The phenomenon was first apparent when Anthony (Jonathan Bailey), the eldest son of the Bridgerton family, became one of the main characters of the show during its second season after a stint on the sidelines in season one.

He effectively replaced Simon Basset (Rege-Jean Page), who was the first season’s primary love interest and de facto leading man.

Anthony’s transition to the lead featured one especially drastic revision: the removal of his large sideburns.

Although they were appropriate for an overbearing eldest brother, Brownell said: “Once we got into his love story, it was like, ‘You gotta go.’”

To fans, this change represented more than just a glow-up: It was a full-blown metamorphosis.

“The sorcery that (Shonda Rhimes) is doing on these Bridgerton men, it needs to be investigated,” declared one TikTok user, in a video that has been viewed more than 16 million times.

For Penelope, the transformation starts with her makeup, which has been radically enhanced.

“In season one, she’s supposed to be the wallflower that literally falls into the wall: You can’t see her,” said Erika Okvist, the show’s lead hair and makeup designer.

“Season two, she’s trying to become a woman, so we’re using quite round shapes, accentuating the roundness of her eyes.”

Season three finds Penelope in a heated romance with Colin, the Bridgerton son played by Luke Newton, a pursuit that informed her look: “To make her eyes more siren-like, as it were, we’re using more angular lines – her eyes look more almond, less round and innocent.”

Colin himself, in his shift from peripheral character to leading man, has also adopted a new look.

Earlier seasons found him plucky and boyish, styled in jaunty pastels that Brownell said “signified his youth”.

Season three Colin, who has travelled abroad and “come back a new man”, has a darker palette reflecting a new worldliness.

“I think the internet has dubbed him Pirate Colin, which isn’t too far from what we intended,” Brownell said.

Notably, the Bridgerton glow-ups do not involve the kinds of bodily overhauls – packing on muscle or slimming down – that are often associated with Hollywood transformations.

In fact, the showrunners cut a plotline from the novel Romancing Mister Bridgerton, which is the basis for season three, that involved Penelope losing weight.

“We think that Penelope is beautiful, and I don’t think it’s really a part of her story,” Brownell told Variety.

John Glaser, the show’s costume designer, said that when a character moves into the spotlight, the wardrobe department takes a pared-down approach.

“When Penelope became the leading lady, we just pulled back,” he said. “We took all of her best attributes and focused on them.”

Playing to Coughlan’s best features meant simplifying her silhouette – even if the changes were not all quite period-appropriate.

“This period does not give women a waistline, and we gave her a waistline,” Glaser said, citing film noir star Lauren Bacall as a reference. “We made her more like a little 50s Dior style.”

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Brownell emphasised that the character dictates the wardrobe, not the other way around: Penelope’s new look reflects her growth as a person, not simply that she needs a makeover because she’s moved up to top billing.

“She’s this character who has been on the sidelines for so long and, appearance-wise, she’s really just done what her mother wanted her to,” she said.

“So she was wearing citrus colours, which are very much Portia Featherington’s favourite palette, and she’s wearing these tight little poodle curls, which is also a Featherington special.”

Coming into season three, Brownell said, her look is "really about separating herself from her mother and her family”.

Coughlan said she wasn’t personally bothered by Penelope’s tawdry pre-glow-up style. But she admitted that dressing for season three was a welcome change.

“It felt soft and romantic and beautiful,” she said. “It was honestly magical.” – The New York Times