Fans of Sex Education will have noticed something curious about the costumes on the hit Netflix show.

The eclectic fashion of the cast of characters – including Eric (played by Ncuti Gatwa), Otis (Asa Butterfield), Maeve (Emma Mackey) and Jean (Gillian Anderson) – seems to have no specific era.

Eighties prints mix and match with grungey Nineties-inspired looks, topped off with the occasional Noughties accent – and this is all purposeful.

"It gives it it’s own individuality," explains costume designer Daniella Pearman, who worked on the show for its fourth and final season, due to air September 21.

We need your consent to load this Instagram contentWe use Instagram to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences

"I do feel like people watching it can feel like: We can be anyone we want to be, we can dress how we want, we don’t all have to own the same snazzy phone or the same designer wardrobe, because everyone can be in their own little world like Moordale [School, where many of the characters were enrolled for seasons one to three]."

With the new season comes new challenges for the characters and new locations – meaning tweaks were made to the costumes to help tell the story.

At the end of season three, Moordale shut down – so now, many of the central characters have relocated to the progressive Cavendish Sixth Form College, which is eco-friendly, technologically advanced and on a much bigger scale than the Moordale students are used to.

"From the beginning, we wanted them to look like their normal Moordale [selves], because it’s only been about eight weeks since the end of the third series," Pearman, 42, says.

"We wanted them to be walking into this new environment and looking like it’s all quite alien to them, that they’re these small fish in this massive pond."

The other big change – which was teased at the end of the last series – is Maeve moving to school in America.

"It’s another different environment from Moordale – very much grown-up compared to Moordale. With her, we didn’t want to totally change her look. We wanted to mature it slightly, but still have the elements of Maeve.

"So the leather jacket, the boots, the fishnet tights – but we had a new vintage leather jacket, new vintage cowboy boots that she might have picked up in a thrift store. Maybe she’s had influences from her new group of friends."

Eric’s style also follows his character arc as he makes a new group of friends, as does Aimee’s (played by Aimee Lou Wood), "As she’s opening herself up to new things, post everything that had happened to her in her past", Pearman says.

"She joins art class and becomes a photographer, and we got this brilliant, arty feel to her."

Maeve's style matures in the new season (Thomas Wood/Netflix/PA)

However, not everyone had a costume glow-up.

"The only one I don’t think really changes dramatically is Otis – but why should he? He’s still trying to find himself, he’s pining for Maeve, he’s been looking after his newborn sister, looking after his mum – he’s not had time to evolve."

As Otis joins the new school and finds a rival sex therapist, Pearman did give him new chinos and put him in a shirt – but it’s small tweaks, rather than anything dramatic.

"When people watch it, that enables the story. It’s not jarring, but shows we had fun developing those characters through their costume."

While Pearman – who got her start in the industry as a trainee on soap Coronation Street in 2004 – struggles to pick a favourite character to dress, she does mention fan favourite Eric, who’s known for bold looks on the show.

"Eric is incredible, looks amazing in anything you put him in and is so collaborative and interested in it," Pearman says – and this season, she wants viewers to look out for the "amazing vintage jackets" she’s dressed him in.

Vintage is a running theme throughout the costumes, with Pearman saying: "We tried to be as sustainable as we could" – particularly as the new school puts the environment front and centre.

"We did shop in vintage stores and charity shops, and stuff is hired from costume houses. Then there’s stuff that has to be bought, because you don’t have the choice or time to have stuff made.

"In telly, things happen quite quickly, and there are last-minute changes. So we needed doubles for stunts or repeats of stuff – if someone’s having a drink spilled over them."

Eric is one of the colourfully dressed characters in Sex Education (Samuel Taylor/Netflix/PA)

If you’re looking to get the vintage vibe of show, Pearman’s advice is to "invest time in it".

When shopping in secondhand stores, she says: "Don’t rush it and enjoy it – and think outside the box. If you see something you really like and you’re like, ‘Where will I wear it?’ Never think that, always find somewhere to wear it."