He told the newspaper there was an emergency meeting at Balmoral Castle, before Charles phoned to chastise Harry, reports News.com.au.
"It is very serious," he said.
After all, she could be end of Britain's royal family.
Max Hastings, from the Daily Mail, bemoaned the "vulgar Hollywoodising" of the young royals and condemned her appearance on the prestigious cover.
"It does not seem cynical to suggest that Ms Markle, for all her beauty and charm, would have been unlikely to achieve such prominence on the strength of her acting achievements, not merely to celebrate the 100th episode of her TV drama Suits," he wrote.
Mr Hastings seemed to suggest the 36-year-old is nothing more than an attention-seeking hussy using the prince to boost her own profile.
He went on to suggest she and Prince Harry are representative of a "narcissistic" generation that could actually bring down the House of Windsor.
"Now that Ms Markle has gushed all over Vanity Fair about her relationship with Harry for no better purpose than to satisfy a yearning for fame, she cannot at some future date reinvent herself as a princess," he wrote.
"The monarchy ... is sustained by a web of delightful illusions and fantasies that are based on the concealment from the eyes of us commoners the humdrum ordinariness of the Royal Family's individual members."
At the other end of the spectrum, The Guardian's Marina Hyde admitted she "can't get enough of the Generation Y royals talking about their feelings".
While she disagreed about Ms Markle's royal potential, that didn't stop her tearing the American's personality to shreds.
"The reader is required to wade through some agonisingly stultifying details as if it's some kind of vision quest," she wrote.
"Meghan has freckles - the freckles get more than 100 words. She's from California - that gets an even longer run-out. Even details of what the interviewer and Meghan ate are presented as holy relics."
To make it clear that she criticised the interviewee and not the interviewer who chose the dull topics of conversation, Ms Hyde said Ms Markle sounds like "a very nice lady" but she projected a "jaw-slacking image of blandness".
If that's the case, she won't have any problem getting on with Wills and Kate.
Surely that's perfect for a prospective princess?
No matter what she does, Megan Markle cannot win.
If she is silent, speculation is wild; if she speaks out, judgment is severe.
The scrutiny she has received has been so intense Prince Harry released a remarkable statement in November last year, warning the public a line had been crossed.
No-one cares that she is smart, with a degree in international studies and theatre from America's prestigious Northwestern University.
It doesn't matter that she's worked with the US embassy in Buenos Aires, or that she's spent a lot of time campaigning for clean water and gender equality as an ambassador for World Vision Canada.
She founded her own lifestyle website - oh, and she's actually quite a good actress.
Nope, the sum total of her worth as a human being seems to have become how good she is as a prospective royal wife.
The world will never stop criticising her nationality, her racial heritage, her marital status, her career projectory, her life choices or her personality.
After all, if the royal family collapses, it will be all her fault.
