The longstanding royal rule one guest almost broke at dinner with the Queen

We all dream of having an afternoon tea with the Queen, and in most cases when asked "Who would you invite to your dinner party?" the answer, is almost always, Her Majesty.

But dining with the 95-year-old royal requires you to follow one simple etiquette rule - eat when the Queen eats.

However, former royal butler, Paul Burrell, has recounted a time when the rule was ignored at an official feast by the local prince on the Royal Yacht Britannia in the South Pacific.

Reminiscing about the awkward moment, to The Guardian, he said: "The prince forgot to watch what the Queen did - instead, he popped the grapes into his finger bowl, then some cherries, then when the cream and sugar came out, he poured them in too, making a kind of fruit soup."

Watching on in horror Paul, 63, said: "I was standing behind the Queen looking horrified.

"He was about to raise the bowl to his lips to drink it when he looked at the Queen and realised he had made a terrible mistake."

Uh oh!

However, Queen Elizabeth II's reaction was pure "class".

Paul added: "Not wanting to make him feel awkward, she picked up her finger bowl and took a sip. Now that's class."

This royal rule dates back to centuries, but is said to still continue on to this day.

But there are some other rules in the royal household.

Not only must you eat at the same time as the Queen, but she has also banned garlic from the royal kitchens, and she likes the crust cut off of her sandwich, if she was to eat starchy foods.

Another secret royal rule is she always takes Earl Grey teabags with her wherever she goes, especially when carrying out royal engagements abroad.

There's nothing like a British brew is there Liz?