'Mrs. Harris Goes to Paris' re-creates fabulous Dior couture

This summer’s most romantic movie is about a woman who falls in love … with a dress.

In “Mrs. Harris Goes to Paris,” out Friday, a plucky, kind-hearted cleaning lady (Harris, played by Lesley Manville) working in 1950s London discovers a Christian Dior gown in a wealthy employer’s closet. The strapless lavender frock, festooned with glittering embroidered flowers and lace trimmings, propels Harris on a quest for her own couture confection, leading her all the way to France and Dior’s hallowed maison.

The film’s costume designer Jenny Beavan told The Post that Harris’ rapturous response isn’t actually that far-fetched, historically speaking.

“For [many] women, it was just fantastic at the end of [World War II] to see clothes that had such volume in fabric, after everybody had been scrimping on rations,” said Beavan, a three-time Oscar winner.

In fact, Christian Dior — who debuted his line in 1947, as Paris’ demoralized haute couture industry was still reeling from the aftermath of World War II and the Nazi occupation — had a knack for driving women wild with his clothes. Literally: Mobs attacked models wearing his early designs on the street, tearing the decadent duds off their backs.

For the film, Beavan had to translate that exquisite excess on screen.

The actual dress that inspired Harris’ delirious desire was the iconic “Miss Dior” gown, made from more than 1,000 silk flowers. Beyond that piece, Beavan and her team created some 20 “Dior” garments — many faithful reproductions of the designer’s iconic pieces from 1947 to 1957.

It “couldn’t be any old thing,” Beavan said of the fashions. “It had to look like Dior, even if it wasn’t. So it was quite a lot of pressure!”

Back in the day, Dior’s atelier attracted the richest and most glamorous women in the world, including princesses and stars like Marlene Dietrich and Grace Kelly.

“Dior’s clients were mainly well-known in the political world, and were rich with good taste,” Luciana Arrighi, the production designer for “Mrs. Harris,” told The Post.

In keeping with his clientele, Dior’s studio was “grand,” with its all-white interiors, hushed ambience and “breathtaking” sweeping staircase, which Arrighi’s team re-created from scratch on set in Hungary, using blueprints and furniture from the fashion label’s archive.

“The atmosphere at Dior was to give reassurance to the richer and renowned,” said Arrighi, who in the 1960s worked as a couture model for Dior’s protégé, Yves Saint Laurent.

When Harris finally gets to Paris — after scrimping, playing the lotto and even dabbling in some horse betting — she unwittingly walks into a Dior fashion show, based on the fashion label’s 10th anniversary couture show in 1957. After a villainous vendeuse (played by Isabelle Huppert) tries to throw the dowdily-dressed Harris out of the building, a kindly marquis invites her to stay as his guest — opening the door for her couture transformation.

Beavan began researching Dior when she was working on her previous film, the similarly fashion-focused “Cruella.” For “Mrs. Harris,” she visited the Dior archive, where she saw “lots of wonderful stuff” — sketches, patterns, fabric samples, books — but hardly any clothes.

“They didn’t see the importance of keeping things in the ‘50s,” Beavan said. “They’d make the collection, sell it and then move on to the next collection.”

Dior lent five outfits from its heritage collection for the film, including the famed Bar Suit, with a pleated, calf-length skirt that took an astonishing 20 yards of fabric to make.

Beavan and her costume-makers, John Bright and Jane Law, then had to re-create the other Dior looks in the film.

Those garments — a sweet lace frock adorned with black ribbons, a sharp-shouldered bolero jacket in cream satin, a chic ice-blue gown with a folded collar — “all have the most extraordinary quality about them,” Bright told The Post. “They’re almost untouchable because they look so beautiful.”

During production, Bright discovered that his costume shop, Cosprop, had a vintage Dior from the same 1957 collection featured in the movie. Seeing how that was put together helped with recreating some of the intricate techniques that Dior’s sewers used — from draping to embroidering to bolstering skirts and collars with layers upon layers of stiff organza.

“He would use up to five layers of organza,” said Bright. “It’s a technique that’s quite costly, because it takes time to do all that stuff,” he said, adding that it took three weeks to make some of the pieces. “It’s one of the reasons why a Dior dress costs so much.”

And that expense, that opulence, had to be captured in “Mrs. Harris” — though at a fraction of the cost.

“We were on a ridiculously small budget and in full-on COVID,” Beavan said, chuckling at the thought of Dior sewing 1,500 floral petals onto a dress. “We didn’t have the time or money to do that, but I am thrilled with how it turned out.”