The Royal family are famous for their love of rules and when it comes to how they celebrate Christmas, it was an unusual tradition that caught newlywed Diana out.
From opening presents on Christmas Eve to weighing themselves before and after the main family meal, the Royals' long list of holiday traditions can be hard to keep track of.
It was something that Princess Diana struggled with during her first Christmas with ner new family in 1981.
The princess was unaware that all gifts given must be of the cheap and cheerful variety, the funnier the better, The Mirror reported.
Instead, the 20-year-old newlywed committed a major faux pas when she gifted Princess Anne a cashmere jumper, who gave Diana a toilet roll holder in return.
Fortunately by the next Christmas Diana had gotten into the swing of things, gifting Fergie a leopard print bath mat.
The Royal family are famous for their joke Christmas presents, with Kate Middleton reportedly giving Prince Harry a "grow your own girlfriend" kit one year.
For her first Christmas with the family last year, Meghan Markle is said to have given the Queen a singing hamster toy.
"Meghan bought a little hamster that sings with a little rope for Her Majesty," a source told the Daily Star in January. "It was so funny, especially when the corgis tried to take hold of the toy."