FROM wearing jeans to touching Prince Harry in public, Meghan Markle has been tearing up virtually every rule in the royal handbook since the couple stepped out together.
That's according to etiquette expert William Hanson, who advises private clients and royalty around the world on everything from dining to dress and maintaining impeccable manners.
He said the royal couple have already ditched several protocols ahead of their Windsor Castle wedding, including the use of "Ms" for Meghan's title, their email RSVP and announcing critical details ahead of time.
"This wedding is probably actually going to be the one wedding that sort of irritates everybody like me because it will break protocol because Meghan seems to have her own take, which is fair enough, on what she wants to do," he said.
"Even things like the cake being announced well in advance. The photographer, the florist. Usually we don't find that out until much closer to the event, if not on the day or after the day. So already we are beginning to see on smaller levels a different sort of thing."
The etiquette expert also said the couple have shrugged off convention in their public appearances in everything from wardrobe choices to how affectionate they are.
"It'll be interesting to see whether Harry and Meghan do continue to hold hands at official engagements once they are married and perhaps Meghan has a bit more experience under her belt," he said, noting that other royal couples including William and Catherine rarely, if ever, touch in public.
"It's just not a British thing. It's a form of emotion and in Britain we normally show emotion to dogs and horses - people are really second rate when it comes to that. It's interesting there is no rule book that says 'do not hold hands' - it's just a precedent thing."
Despite her fashion choices often selling out online, Mr Hanson has previously said her royal style could "irk traditionalists" and has missed the mark at times.
"Meghan's first official outing as a fiancee may have been a media success but with a properly fitting coat and hosiery it would have been more successful," he said after her first appearance with Prince Harry to announce their engagement wearing "white after Labour Day, no tights and a coat that was too short".
The comments provide a harsh reminder of the royal world Meghan has entered based on centuries of tradition in a culture that does not like "reinventing the wheel". The former Suits star will be forced to get to grips with a huge range of unwritten rules covering everything from who to curtsy to, (yes, even Prince George, Princess Charlotte and the new royal baby once they come of age) and what she can wear, say and do in public (no denim, trainers or anything political, thanks).
However at 36, with a range of life experience, the support of Prince Harry and the "softening" of the monarchy in recent years, Mr Hanson said she'll likely be able to carve her own niche in the role. While some older courtiers may have "bristled" at her divorce, the fact Prince Harry is not directly in line to the throne also affords the couple more freedom, he said.
"I mean this in the nicest possibly way … it doesn't sort of matter," he said about the fact Harry is not directly in line to the throne. "Especially now they've had George, Charlotte and there's another one on the way, so actually they can be a little bit more relaxed about it," he said.
As for the royal faux pas, Meghan is in good company with President Obama, his wife Michelle, Julia Gillard, Paul Keating, LeBron James, Ed Sheeran and David Beckham all making very public gaffes by being too touchy, verbose or wearing the wrong thing at the wrong time.
On the big day, the wedding dress code could also be an issue with divorced brides technically supposed to wear a "day dress" rather than white and shoulders not meant to be seen in church. Mr Hanson said viewers likely won't know in advance whether Prince Harry will wear military dress like Prince William did or a more casual morning suit and shave his beard.
"This is my worry with Americans watching the wedding. I think that they think you're going to get what happened in 2011. St George's Chapel is smaller. Prince Harry is not Prince William, you're not going to have the grandees there," he said about the fact politicians have not been invited.
As for tips for anyone lucky enough to score an invite, make sure you read the dress code properly, don't wear brand new shoes and practice sitting, eating and standing in your outfit to ensure it's comfortable, Mr Hanson said.
And if all else fails: "Just watch your host or the most learned guest and copy them."