In 2012, French magazine Closer published topless photos of Kate Middleton secretly snapped by paparazzi during a vacation in southern France. The timing couldn’t have been worse: Middleton and her husband Prince William were on an official tour in Asia.

While Buckingham Palace called it “grotesque,” the scandal not only revealed her naked bits, but also the promise she showed as a future monarch.

“She conducted herself with so much grace that day,” royal expert Victoria Arbiter told The Post. “There wasn’t any sense that she was upset or fazed or flustered. And, of course, she would have been. But the fact that she recognized she had a job to do. There’s a steeliness and a determination to do well.”

Middleton’s keep-calm-and-carry-on attitude was reminiscent of a towering figure in British society: Queen Elizabeth II — and suggested that Middleton, who was raised a commoner, had been absorbing valuable lessons from her husband’s grandmother.

But according to Arbiter, Middleton, who met Prince William at St. Andrews in 2001 and married him in 2011, had been learning more through observation and osmosis — not formal lessons.

“People love to say that the queen is running princess school, and she’s got Kate in a classroom with a blackboard and telling her how to do things. It’s just not how it works,” said Arbiter.

Queen Elizabeth, who was crowned in 1953 and died at the age of 96, had provided a stellar example for Middleton, now 40, who has taken to heart her approach to the job in many areas including her sense of duty, her steadiness and even her approach to fashion.

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“[Elizabeth] is very keen on members of her family finding their own way, and I will be paraphrasing, but Prince William said a few years ago, she doesn’t tell you what to do or how to do it. She lets you know if she doesn’t like how you did it.”

And in one particular instance, the monarch had signaled to Middleton and the public that she most definitely approved of her role in the Firm.

In May 2020, Middleton announced “Hold Still,” a photography project that sought to capture the country’s resilience during the COVID-19 pandemic.

Months later, Elizabeth wrote a letter praising the entrants, saying, “The Duchess of Cambridge and I were inspired to see how the photographs have captured the resilience of the British people at such a challenging time, whether that is through celebrating frontline workers, recognising community spirit or showing the efforts of individuals supporting those in need.”

Arbiter said that by simply issuing the letter, “It was putting support behind the initiative and showing praise for Kate without saying, ‘Great job’. She does things in a very subtle fashion,” noted Arbiter.

And while there is no blackboard or classroom, the queen had brought Middleton on a few official engagements to observe firsthand. In 2012, Prince Charles’ wife Camilla Parker Bowles and Middleton accompanied the monarch to Fortnum & Mason, an upscale department store, for an official engagement.

“It was the first time the queen had two future queen consorts conducting an official engagement together,” noted Arbiter.

Other visits followed. Also that year, during the Diamond Jubilee in honor of Queen Elizabeth, Middleton spent the day with the monarch and Prince Philip in Leicester. The next year, while pregnant with Prince George, she was with the pair at a Baker Street tube station for an event.

“She’s also taken a leaf out of Prince Philip’s book, because he was the perfect blueprint for how to conduct oneself as a royal consort, and I think she took guidance from him, too,” said Arbiter.

Being a working royal also means striking the appropriate balance with clothing and presentation, an area where Middleton has evolved considerably since she first arrived on the scene in dresses from Reiss and LK Bennett, the brand that also made her favorite nude pumps.

Royal fashion commentator and author of “HRH: So Many Thoughts on Royal Style,” Elizabeth Holmes said Middleton has harnessed style in an intelligent way, adopting some tried-and-true fashion principles from the monarch.

“The queen is so singular in the way she approaches her job and her wardrobe. I see a lot of similarities between Kate and the queen … It’s very subtle incorporation of certain things,” said Holmes.

First among them is dressing in a singular color.

“The queen is known for wearing a bold color. It serves a real purpose and helps the queen to be seen. Kate knows that, and she often dresses in a single, solid bright color,” said Holmes.

She pointed to a recent Buckingham Palace garden party where Middleton attended in a head-to-toe coral pink ensemble. “It was a pink hat, pink coat, pink shoes.”

Like the queen, Middleton also relies on a small stable of designers.

“It’s a trust and efficiency thing. She has always done that, and Kate very much does that, too. The attention on Kate’s fashion is such that it is wise for her to sprinkle around the goodwill by wearing British brands, but she returns all the time to a trio: Alexander McQueen, Jenny Packham and Catherine Walker,” said Holmes.

She added, “They know her and the demands of a working royal wardrobe. It’s not just about looking pretty.”

The clothing needs to withstand the weather elements and avoid wrinkling or cinching up when she waves or crouches to speak to someone.

Also like Elizabeth, who always had a hat and her handbag that draped over her arm, Middleton relies on the same accessories like a clutch purse and a pointy-toed pump.

Beyond the clothing, the pair have a similar “steadiness.” Holmes said that the queen was stoic in public while Middleton is more modern and quick to smile, but the duchess has clearly picked up being consistent at events.

“I think the royal family prides themselves on their ability to hold steady with their public appearances. Kate has done a great job of following the cadence,” Holmes said.

Both Arbiter and Holmes noted that Elizabeth and her grandson’s wife already had much in common, so perhaps she was a natural student.

They are both sporty, outdoor types, who love animals and the countryside and feel most at home away from the camera.

“Kate by nature, similar to the queen, is actually quite shy,” said Arbiter, adding, “She doesn’t crave the spotlight. She’s not flashy.”