There was one royal who put her foot down when it baby names — and it wasn’t Meghan Markle.

The 37-year-old’s mother in law, the late Princess Diana of Wales, once revealed she was behind the names of her sons, Princes William and Henry – who goes by his nickname Harry – in royal biographer Andrew Morton’s book “Diana: Her True Story.”

PRINCE HARRY WILL BE A HANDS-ON PARENT LIKE DIANA, SAYS ROYAL BIOGRAPHER

The book was based on the secretly recorded conversations between the princess and her friend, James Colthurst, before her divorce from Prince Charles in 1996.

This is a 1984 file photo shows Britain's Princess Diana with sons Prince William, foreground, and Prince Harry. Long dismissed as a party boy, Prince Harry has transformed himself in the public eye and enjoys widespread popularity as he prepares to marry Meghan Markle on May 19, 2018. Harry has become a forceful advocate for veterans and won admiration by speaking openly about his struggle with the pain caused by the early death of his mother, Princess Diana. (AP Photo, file)

This is a 1984 file photo showing Britain's Princess Diana with sons Prince William, foreground, and Prince Harry.  (AP Photo)

“The alternative was Arthur and Albert,” Diana once shared, as reported by People magazine. “No, thank you.”

“There weren’t fights over it,” added Diana. “It was just a fait accompli.”

However, the magazine noted both “A” names did make the cut. Her older son’s full name is William Arthur Philip Louis, while Harry’s is Henry Charles Albert David.

Markle, an American actress who became the Duchess of Sussex in May 2018 when she married Harry, is due to welcome their firstborn sometime this spring.

PRINCESS DIANA: 'BOY, WAS I TROUBLED'

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Princess Diana puts on shoes for little Prince Harry as her other son Prince William squints from the bright sun during their vacation with the Spanish royal family at Marivent Palace in Palma De Mallorca. (Reuters)

According to People magazine, if the couple were to follow royal tradition, the world won’t know their son’s or daughter’s name as soon as he or she is born. Instead, the baby’s name will be announced a few days after the birth. It is likely the sex of the baby will be revealed, along with the birth announcement. In the case of William and Kate Middleton’s third child, the world had to wait four days after the birth to learn his name was Louis Arthur Charles.

And the name holds special significance, as expected within royal tradition. It is believed to be a tribute to Prince Philip, whose grandfather was Prince Louis Alexander of Battenberg. The magazine claimed the name holds a special place for Prince Charles, who’s beloved great-uncle and mentor, Earl Louis Mountbatten, was assassinated by the IRA in 1979.

In the case of William and Middleton’s other two children, Prince George and Princess Charlotte, their names were revealed two days after their royal births.

But it’s possible Middleton, the Duchess of Cambridge, 37, broke royal tradition when it came to releasing her baby names. People pointed out that William’s name wasn’t announced for a week. And as for his father Prince Charles, it took an entire month.

Britain's Prince William and Kate, Duchess of Cambridge with their children Prince George, right, Princess Charlotte, center, and Prince Louis.

Britain's Prince William and Kate, Duchess of Cambridge with their children Prince George, right, Princess Charlotte, center, and Prince Louis. (Matt Porteous/Kensington Palace via AP)

MEGHAN MARKLE WANTED TO BE 'DIANA 2.0,' CLAIMS ROYAL BIOGRAPHER

U.K. bookies Ladbrokes, which have been taking bets on the baby’s name, suspect Markle and Harry will possibly pay tribute to his mother Diana somehow. Other names they’re betting on include Elizabeth after the queen, Alice, Mary and Alexandria.

For boys, names in the running include Albert, Arthur, Philip, Alfred, Charles, James and Alexander.

As for the royal birth, Diana admitted she felt such intense media scrutiny that it proved to be “unbearable.” Consequently, she was induced — but she and Charles had to pick a day that didn’t interfere with Charles’ polo schedule.

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Britain's Prince William, the 6-month old son of British Prince Charles and Princess Diana, during a special picture call at Kensington Palace in London. (Associated Press)

“When we had William, we had to find a date in the diary that suited Charles and his polo,” Diana explained in Morton's book. “William had to be induced because I couldn’t handle the press pressure any longer, it was becoming unbearable. It was as if everyone was monitoring every day for me.”

Still, Diana admitted that the arrival of William, now 36, was worth it all.

PRINCESS DIANA'S NIECE TELLS ALL

“Anyway, the boy arrived, great excitement,” she described. “Thrilled, everyone absolutely high as a kite — we had found a date were Charles could get off his polo pony for me to give birth. That was very nice, felt grateful about that!”

However, the birth of Harry, now 34, came with its own set of problems. Diana said that Charles had always wanted a girl and was in for a big surprise.

Princess Diana, along with Prince Charles, left St. Mary's Hospital in London with Prince Harry on Sept. 16, 1984. Harry was born the day before.

Princess Diana, along with Prince Charles, left St. Mary's Hospital in London with Prince Harry on Sept. 16, 1984. Harry was born the day before. (AP)

“I knew Harry was going to be a boy because I saw on the scan,” she explained. “Charles always wanted a girl. He wanted two children, and he wanted a girl. I knew Harry was a boy, and I didn’t tell him.”

When Diana delivered their second son, Charles allegedly didn’t hide his disappointment.

“First comment was ‘Oh God, it’s a boy,’ second comment: ‘And he’s even got red hair,’” claimed Diana.

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Diana also revealed Charles expressed being let down again during Harry’s christening. He allegedly told her mother, “We were so disappointed — we thought it would be a girl.”

“Mummy snapped his head off, saying, “You should realize how lucky you are to have a child that’s normal,’” said Diana. “Ever since that day the shutters have come down, and that’s what he does when he gets somebody answering back at him.”

Prince William makes a royal salute as he watches the scene of Trooping the Colour from the balcony of Buckingham Palace with his brother Harry and mother Princess Diana on June 15, 1985 in London.  REUTERS/Roy Letkey - RTR1JWRG

Prince William makes a royal salute as he watches the scene of Trooping the Colour from the balcony of Buckingham Palace with his brother Harry and mother Princess Diana on June 15, 1985 in London.  (REUTERS/Roy Letkey)

Diana also described how her rocky relationship with Charles improved before Harry was born. In fact, Diana insisted that she and Charles were “the closest we’ve ever, ever been and ever will be” in the six weeks leading up to the arrival of their second child.

That didn’t last.

“Then suddenly, as Harry was born, it just went bang, our marriage,” Diana admitted. “The whole thing went down the drain.”

PRINCE HARRY 'KNEW HOW TO SAVE HIMSELF'

Diana found a sense of happiness in marriage with the birth of their two sons. The former couple welcomed William in 1982, followed by Harry in 1984. Morton claimed that while Diana was pregnant with Harry, she and Charles experienced an intimate connection, one that involved him reportedly writing love notes to his wife. But after Harry was born, the relationship soured until they finally divorced.

Princess Diana and Prince Charles look in different directions, November 3, during a service held to commemorate the 59 British soldiers killed in action during the Korean War. - PBEAHUNIVAX

Prince Charles and Princess Diana. (Reuters)

“As the boys got older and became like her counselors and friends as sons, she began to enjoy life a lot more,” said Morton to Fox News in 2017. “Diana was very protective of William and Harry. [If] you ever criticized the boys... she would be on you like a tigress. She was the only one who could criticize those two. Of course, she indulged them… She wanted to be a full hands-on parent herself. And interestingly, Prince William recently said the same about his own children. He wants them to enjoy a relatively normal upbringing.”

Diana and Charles finally divorced in 1996. A year later, Diana died in 1997 at age 36 from injuries she sustained in a car crash in Paris.