The National Gallery was the grand setting for the party that followed The Devil Wears Prada 2’s London premiere this week. Donatella Versace held court in a roped-off area beneath Paul Delaroche’s The Execution of Lady Jane Grey.

Meryl Streep, reprising her role as Miranda Priestly – Anna Wintour’s fictional alter ego – wore a red satin Prada coat as a nod to the film’s title and black sunglasses as a wink to Wintour. Glossy magazine editors from Spain, Germany and the Netherlands, flown in for the night, nibbled on fried chicken served with caviar and dishes of mac and cheese presented theatrically under silver cloches.

It is ironic that the most glamorous and high-profile moment the fashion industry has known in years is the release of a film that ruthlessly satirises its demise. “It has kind of blown our minds how much we have been embraced by businesses that we poked fun at in the first movie and continue to poke fun at in the second movie,” said the film’s screenwriter, Aline Brosh McKenna, speaking from her home in Los Angeles.

The plotline of the sequel revolves around Priestly’s attempts to steer Runway magazine through the decline of print publishing. Details of the film are still under embargo, but glossy magazine staffers who attended the film’s premiere described the plot, off the record, as “close to the bone”.

A sequel 20 years in the making shines a spotlight on an industry that has been turned upside down by the collapse of legacy publishing. But the razzmatazz around the film’s release confirms that fashion is as compelling as ever. “What is amazing about fashion is that it never loses its appeal,” said the film’s director, David Frankel. “Humans are drawn to beauty and to glamour and to remaking our identities using clothing.”

The novel from which the franchise grew, written by Lauren Weisberger, a former assistant to Wintour, was denounced as high treason by fashion insiders when it was published in 2003, and designer brands refused to lend clothes for the film for fear of offending Vogue.

Twenty years on, the tables have spectacularly turned. The sequel is bursting at the seams with eagerly lent designer pieces, and willing cameos from Versace and other industry insiders. In the real world, fashion industry power brokers have been humbled and reconfigured both by the move to digital, with readers abandoning newsstands and editorial increasingly reliant on commercial partnerships.

Gatekeeping has evaporated in a cultural shift away from institutional power – shoppers are no longer prepared to obediently buy into trends directed by catwalk designers and magazine editors.

The Devil franchise, a symbol of the glory days of lavish shoot budgets and bottomless expense accounts, is no longer seen as a takedown. Instead, it has become a beloved part of fashion’s self-mythology, and editors and designers are falling over themselves to get on board with the hype around the sequel.

In the new film, Emily Blunt’s character, Emily Charlton, has jumped ship from the magazine to work for a luxury brand and now wields power over her old boss. Editors who once dictated taste according to their whims have to play nice with commercial partners they were once too grand for.

“The media business is frightening today,” says Frankel. “The same is true of Hollywood. There’s a terrible contraction – we all see the tsunami of AI coming and we are all just doing anything we can to survive. The movie is addressing all of that. The first film was a coming-of-age story, this one is about values and morals. I see Miranda as heroic. She’s steering a ship through rough water and determined to find land.”

The publicity around the return of the Devil shows the remarkable extent to which Wintour has come through two such bruising decades unscathed, having turned a snipey book by an assistant she claimed not to remember into the centrepiece of her own personal mythology. A year after she officially stepped down from the editor’s chair at American Vogue, she appears on this month’s cover alongside Streep: a clear signal that she remains the industry’s leading lady.

The new film and its attendant buzz also highlights changing attitudes to older women. Streep and Wintour’s joint appearance puts two 76-year-old women on the cover of Vogue, photographed by another 76-year-old woman (Annie Leibovitz) and styled by 84-year-old Grace Coddington.

The age-old sexism of Hollywood and the fashion industry, which preferred women over 40 out of sight, has been challenged by the power of celebrity which sees women such as Streep and Wintour create enduring personal brands which retain box office power.

“Fashion creates these iconic women with staying power,” says Brosh McKenna. “I’m thinking of Coco Chanel, Diana Vreeland, Iris Apfel. It’s a business where people work till they drop, and I quite like that.”

In the 20 years since the first Devil Wears Prada, the prices of designer items beloved of the fashion industry have soared, thanks to what might be called fash-flation. Here are some examples of pieces worn in 2006 and what they would cost today:

Chanel jacket

Post-makeover, Andy Sachs (Hathaway’s character) wears a double-breasted Chanel jacket. At the time, a jacket from the brand would have cost about $4,800 or £3,561. Now a jacket in the pre-collection is priced at £6,430, an 80% increase.

Fendi bag

Although the Chef bag in Devil Wears Prada is discontinued, a Baguette from the brand can still be bought. Priced at $1,500 (£1,112) in 2006, they are now £2,750, a 147% increase. Chefs, meanwhile, are available on the resale market. One on FarFetch is a snip at £753.

Jimmy Choo shoes

“You sold your soul to the devil when you put on your first pair of Jimmy Choos,” Emily tells Andy in the 2006 film. At the time, a pair would have cost at least $385 (£281). Now, a classic pair of sandals from the brand is £625, an increase of 122%.

Hermès scarf

Always a favourite of the fashionable, Runway editor Miranda Priestly wore the Hermès scarf in the original film. At the time, it would have cost about $320 or £237, but 20 years later, a classic scarf from the brand is £520, 119% more expensive.