In the days leading up to her wedding to Prince Harry, Meghan Markle received stern words from Queen Elizabeth II over eggs, according to a royal expert.

Katie Nicholl, a British best-selling author and royal correspondent for Vanity Fair, said Markle had insisted on there being a “macrobiotic alternative” for some of the Hollywood star guests attending the ceremony who follow the diet.

“[Meghan] got very upset when she felt that she could taste egg in a dish when she was told there was no egg in there, and she said, ‘No, I can taste it, I can taste there’s egg in this dish,’” Nicholl told Yahoo’s Royal Box Friday.

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“I think there was a bit of an upset when suddenly the queen walked in because of course, this was Windsor Castle, this is her home,” continued Nicholl. “And she just quietly took Meghan to the side and said, ‘Meghan, in this family, we don’t speak to people like that.’”

Nicholl recently published “Harry and Meghan: Life, Loss, and Love,” which presents an in-depth look at Harry’s romance with the former American actress and how their high-profile union is reshaping the monarchy. It features interviews with friends close to the couple, those who have worked with Harry, as well as palace aides, among others.

Markle, 37, became the Duchess of Sussex when she married Harry, 34, in May 2018. The couple is expecting their first born any day now.

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It wouldn’t be the first time the reigning monarch, 93, intervened during the planning of the royal wedding. Markle previously came under fire for allegedly choosing a tiara that Elizabeth didn’t approve of.

Royal journalist and author Robert Jobson told Royal Box in March that the alleged tiara incident, in which Markle allegedly threw a tantrum when Elizabeth denied her an emerald tiara for the royal wedding, may have been more of Harry’s fault.

“I don’t think Meghan was being difficult when she was picking out a tiara,” said Jobson. “I think Harry was probably being overly defensive and overly protective.”

While Jobson defended Markle in the alleged tiara dispute, he believed there was some rift or incident between the star and Kate Middleton, the Duchess of Cambridge, who reportedly cried at a dress fitting for her daughter Princess Charlotte leading up to the royal wedding.

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“Whether or not there were reports Kate cried… I don’t know if that’s true or not, but there’s clearly been some confrontation,” said Jobson.

Nicholl previously told Fox News that Markle has since developed a close bond with the queen since becoming a member of the British royal family.

“I’ve been quite impressed by how much responsibility the queen has given Meghan,” Nicholl explained. “The queen likes Meghan. She recognizes how happy Meghan makes Harry, but she also sees how capable Meghan is as a royal. She showed them how much she thought of Meghan in the early days before they were actually married when she invited Meghan to be a part of the Commonwealth Day service. Quite an important event in the royal calendar. And there was Meghan before she was actually married into the royal family.”

Nicholl claimed Elizabeth is so fond of Markle she did more than invite her to personal, intimate family gatherings leading up to the marriage — she put her to work as a future duchess.

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“The queen put Meghan on that world stage before she was even a member of the royal family,” said Nicholl. "I remember being really struck by that, surprised and impressed. The way Meghan has been fast-tracked into the royal family has been quite unique.”

Perhaps Elizabeth could sense that her grandson was deeply concerned about what the future held for him before he met Markle through a mutual friend.

“Harry, at one point, was genuinely worried that he was going to be left on the shelf,” Nicholl previously told Fox News. “His brother was happily married with children. Many of his friends, who up until that point had been eternal bachelors, were getting engaged, getting married. I think Harry genuinely worried about that, and one of the reasons he worried about that was because he wanted to find his life partner, and he wanted to be a dad. Harry wanted children for a very long time.”

After saying “I do” in a televised ceremony watched by 29 million people, Markle and Harry revealed to the world in October of last year that they were expecting. Nicholl wasn’t shocked by the news.

“As soon as they were married, they wanted to start trying for a family,” Nicholl claimed. “They were both apparently surprised and delighted that it happened as quickly as it did. … Anyone that has seen Harry with children knows there is a magnetism there… He has this incredible ability to connect. He has real empathy for them. He’s simply brilliant with kids and, I think, will be a brilliant father. I know it’s something he’s wanted for a long time.”