How Meghan Markle is rocking the royal family

It’s been just over six months since Meghan Markle joined the British royal family. The moment the American said “I do” to Prince Harry, her contract began with “The Firm,” as it’s affectionately known in the UK.

And the 37-year-old former “Suits” actress has been flying the American flag high as she stamps her unique personality on the institution of the monarchy.

She has blown off dated traditions with her multicultural wedding, liberal leanings, rebellious fashion sense — she wore an above-the-knee skirt to the theater in August, something sister-in-law Kate Middleton would rarely do. Meghan was even at the center of a June kerfuffle when Irish politician Catherine Noone tweeted that the Duchess had told her she was pleased about the country’s recent referendum result on legalized abortion. (It’s seen as verboten for royals to be political.)

Of course, much of it is just the former starlet acting like a normal person — and highlighting just how ridiculous and old-fashioned royal protocol can be. In September, the duchess made headlines and was hailed as a feminist simply because she shut her own car door after stepping out at London’sRoyal Academy of Arts. Such a menial task is usually reserved for a flunky.

But the winds are changing in the stuffy old House of Windsor thanks to the mixed-race Californian beauty. Take a look at the easy, breezy portraits that marked Prince Charles’ 70th birthday, complete with lots of laughter and Charles cuddling his grandkids (something we never saw him doing with his own boys). Meghan is letting everyone know that it’s OK to loosen up a bit.

Even the way Prince Harry and Meghan interact in public — the constant touching and adoring glances — seems to have influenced the other royals. Take Prince William and Kate, who have always behaved in a very stiff, formal way that feels more out of the Victorian era than the Instagram age.

In a rare exhibition of tenderness at the wedding of William’s cousin Princess Eugenie to Jack Brooksbank in October, the parents-of-three were seen holding hands. At one point, Kate placed her palm on William’s thigh, a move that’s miles away from her usual habit of keeping a few modest inches between her and her spouse.

English journalist Phil Dampier told The Post the Duchess of Sussex is ­really shaking things up. The go-getter, who has a previous marriage behind her, didn’t grow up in awe of the royals in the way that the more deferential Kate was raised.

“Meghan has hit the ground running,” said the author of “Royally Suited: Harry and Meghan in Their Own Words.” He went on to explain that her American openness and experience as an actress has helped smooth her path.

“Princess Diana and Kate Middleton were very nervous when they first started out in the royal family, but Meghan is an already accomplished public speaker,” said Dampier. “She’s also helping Harry with his speeches . . . he is increasingly doing them without [the need for] notes.

“Meghan has not put a foot wrong.”

Although she was criticized a bit for her awkward fashion choices immediately post wedding, she has quickly sharpened her style, favoring figure-hugging designs and eschewing headgear. The newlyweds triumphed on their recent tour of Australia, New Zealand, Tonga and Fiji where they enchanted fans with their outgoing manner and Princess Diana-like ease with ordinary folk. Whereas Kate tends to keep a safe distance between herself and Queen Elizabeth’s subjects, Meghan has no problems hugging people across the crowd-control barriers.

Of course, some Windsor watchers will always find something to complain about. When the Duchess of Sussex announced her pregnancy five months after marriage, there were mutterings that the 37-year-old would be a “geriatric mother.”

Eyebrows were also raised earlier this month by the sudden departure of a personal assistant on Harry and Meghan’s staff. It followed the resignations of communications secretary Katrina McKeever from Kensington Palace in September and Harry’s former right-hand man, Edward Lane Fox, who is believed to be leaving his post earlier than expected.

Dampier believes the latest assistant’s exit is a red herring: The employee turnover rate at Buckingham Palace is notoriously high due to the low salaries. But Ingrid Seward, editor-in-chief of Majesty magazine, is not so sure.

“There’s lots of rumors swirling around that Meghan is a diva and staff are leaving because of it,” she told The Post. “They are saying that she’s upset Kate and William, too. She’s not the most popular girl on the block.”

It was just announced that Meghan and Harry are moving from their digs in Kensington Palace (where William and Kate also live) to Windsor, outside of London, in the New Year.

Dampier, former royal correspondent for The Sun newspaper of Britain, believes there may be some competitive feelings coming from Kate who was on maternity leave when Meghan first burst onto the scene.

“There’s no hard evidence for it, but I’m sure there will be a little bit of jealousy,” he said. (To be fair, Kate is likely under more pressure to be perfect given that she will presumably be the Queen of England one day.)

While the American-born Meghan is a ­favorite of Britain’s middle and lower-middle classes, some members of the elite have yet to be won over.

“The Establishment is slightly skeptical of her jetting off to all sorts of deprived places and holding the hands of the unfortunate,” said Seward, author of “My Husband and I,” about the 70-year marriage of the Queen and the Duke of Edinburgh. “I think they feel she is too much of an actress.”

Still, the Duchess of Sussex has a full calendar and is a hard worker. She is said to rise at 5 a.m. and sends six or seven texts a day to staff with ideas and requests.

Added Seward: “[Working hard] is a very admirable trait as far as the British people are concerned.”