The Queen has refused to talk about Meghan Markle and Prince Harry during her riding trip, according to a royal insider.

Those spending time with the monarch, 93, have one "very strict rule" to follow, which is to avoid speaking about the Sussexes - who recently skipped a trip to Balmoral.

Journalist Quentin Letts revealed the taboo topic his friend was told to avoid mentioning on social media.

MEGHAN MARKLE, PRINCE HARRY ARE 'PR DISASTER' FOR THE ROYALS

He tweeted: "Friend of an acquaintance was about to go riding with HMQ.

"Was given v firm advice 'Talk about anything except one subject.'

"Brexit? 'No, The Sussexes.'"

KATE MIDDLETON, PRINCE WILLIAM FLY COMMERCIAL FOLLOWING MEGHAN MARKLE, PRINCE HARRY PRIVATE JET BROUHAHA

Queen Elizabeth II has reportedly refused to discuss

Queen Elizabeth II has reportedly refused to discuss "The Sussexes." A new report alleges that the monarch has been disappointed in Prince Harry and Meghan Markle's behavior. (​​​​​Getty)

ROYAL EXPERT: PRINCE HARRY, MEGHAN MARKLE'S 'DETRIMENTAL BEHAVIOR' MAY BOTHER PRINCE WILLIAM

The Duke and Duchess of Sussex are the Queen's neighbors, as they moved into Frogmore cottage in April to be close to Harry's grandmother's Windsor Castle abode.

The Surrey mansion is undergoing major building works, including a "$4,969 outdoor seating and cooking area."

According to the Daily Mail, royal sources claim the couple have installed a "cozy" outdoor entertainment area with "patio decking" and "lovely countryside views."

KATE MIDDLETON, PRINCE WILLIAM 'BARELY KNEW' MEGHAN MARKLE BEFORE ROYAL WEDDING TO PRINCE HARRY

Their five-bedroom property, which was a gift from the Queen, was said to have required a “substantial overhaul” before they were able to move in earlier this year.

The subsequent refurb has cost taxpayers a whopping $3 million, sparking fury from campaigners.

The couple’s new residence now boasts a designer kitchen and a refitted bathroom.

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They have also had new heating, wiring and utilities completed, although it was previously reported Harry, 35, asked the Queen to live in Windsor Castle with her and Prince Philip.

This article originally appeared in The Sun.