The concept of food and the royals is historically a bit fraught. According to newspaper memos leaked last year, Her Majesty got irate with her royal protection officers when they kept eating her private stash of Bombay Mix (who can blame her?)

If you're actually invited to eat with the royals - as opposed to just nicking their snacks - the rule of thumb is to follow your host's lead. So if the Queen is standing, you too should be standing (unless she's giving a speech). Wait until she is seated and then take your place. Take all your cues from her, or whoever the ranking royal is at the event in question.

Paul Burrell, former royal butler, recalls a particularly awkward incident on the Royal Yacht Britannia in the South Pacific, where a local prince forgot to take the lead from the Queen.

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

From greetings to small talk and personal space, the baffling and bizarre rules of royal etiquette