Meghan Markle and Prince Harry has angered Queen Elizabeth over their constant war with the royals.
As a result, the 95-year-old monarch has issued them a final warning, according to the Mail on Sunday's diary editor Charlotte Griffiths.
Responding to whether Harry knows of the fact that the Queen has fired a "warning shot", Griffiths said, "How can he not, when the Queen lays down the law you've got to be a bit rattled.
"He does know how all of this works, Meghan maybe didn't and he should have explained if not.
"He has been here for many years and if he's suddenly forgotten this is how the game works and he knows that better than anyone."
She added: "You've got to think they've never quite learned the nuance of it, have they?
"It's been a couple of years now and they still don't seem to get but they just don't, they're just so American about everything. It's a different ball game, they're going to have to learn," Griffiths concluded.
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