Meghan Markle's new challenge: Master British royal protocol

LONDON - From curtsying to Queen Elizabeth to calling her "Your Majesty", American actress Meghan Markle will have to learn her royal lines when she marries Prince Harry and joins the ranks of the British monarchy.

Unwritten rules govern how the royals should behave and the public act around them. While many antiquated protocols have fallen by the wayside, there is still some etiquette Markle will be expected to follow after her wedding to the Queen's grandson on May 19.

"The problem is that she's got to remember that, as a member of the royal family, she represents the family or, as it's been called, 'the brand'," said Mr Grant Harrold, who served as a butler to Prince Harry while working for his father, Prince Charles.

"So, I think there is quite a lot of pressure to make sure she gets it right because the last thing she wants to do is do something wrong... and it ends up becoming front page news - and then it's embarrassing for her and the royal family," he added.

For someone who grew up in Los Angeles, life behind palace walls - where butlers, footmen and members of the royal household discreetly go about their jobs - could scarcely be more different

"I think Meghan will cope - but she will find some of the flummery difficult to bear," said Andrew Morton, who has penned a biography of the bride-to-be.

"This was a girl who was a gender equality advocate for the United Nations - having to bow and curtsy to the Queen and even (her future sister-in-law) Kate Middleton in private occasions."

Strict protocol also dictates that Markle should walk backwards from the Queen in her presence, although Mr Harrold said you would not see this in public. But as the monarchy evolves and modernises, these conventions are not as important as they once were, something the royals themselves acknowledge.

Those who breach the unspoken rules can sometimes expect a frosty reception.

Last year, the governor-general of Canada admitted breaking protocol by touching the Queen's arm during an engagement in London.

Australian prime minister Paul Keating was dubbed the "Lizard of Oz" by the British press after he appeared to put his arm around the monarch's shoulders in 1992.