In reponse to reports of an alleged snub on Meghan’s birthday last week, Mr Rae said: “There is some suggestion that she [the Queen] sent Meghan a private birthday message.

“There’s a suggestion that she has decided that the royal website, Twitter and Instagram will no longer send birthday greetings out to any non-working members of the Royal Family unless their birthday ends in a zero.”

Having celebrated her 41st birthday on August 4, Mr Rae noted that this means Meghan will “have to wait another nine years” before she gets a social media birthday message.

Beatrice will have to wait another six years as she turned 34 on August 8.

He added that Harry, who turns 38 next month, will have to wait until September 2024 for a public birthday message.

Mr Rae also pointed out that the Duke and Duchess of Cambridge and Prince Charles and Camilla, the Duchess of Cornwall “both sent birthday greetings to Meghan”.

Speaking of their birthday messages to Meghan, he added; “It’s obviously opened up some gossip, oh it’s the Queen, she’s snubbing Meghan and everything else.

“You could look at that as a snub but I’d be surprised if she has not sent a private message to Meghan.

“I mean she is her granddaughter-in-law”.

On their official Twitter account, Prince Charles and Camilla wrote: “Happy birthday to The Duchess of Sussex!”, along with a photograph of Meghan earlier this year.

In their Twitter message, similar to Prince Charles and Camilla, Kate and Prince William wrote: “Wishing a happy birthday to The Duchess of Sussex!”.

Meghan and Harry were working royals until 2020, when they decided to step down from The Firm.

Prince Beatrice and her younger sister, Princess Eugenie, 32, have never been senior working royals.