Meghan Markle and Prince Harry: A royal shake-up

This is no ordinary royal engagement.

Meghan Markle brings something different to the British Royal Family.

She is American, divorced, an actress and mixed race.

She is also a campaigner with a variety of humanitarian interests and won't want her marriage to limit her ability to speak out and support various causes - particularly those of gender equality.

As an advocate for UN Women, Ms Markle has worked on helping young girls reach their leadership potential. When she was first approached about working with the United Nations the Suits star insisted on undertaking a period of "work experience" first.

In her own time she shadowed Elizabeth Nyamayaro, a senior advisor at UN Women. Elizabeth was impressed by the intelligence, commitment and curiosity of the actress.

The pair have since worked together closely on a number of UN missions and Elizabeth has no doubt that her friend and colleague will thrive in her new royal role.

"Her ability to listen, her passion for other people, wanting to create social change with that level of platform can only be a positive thing. She'll be fine, she'll be great in fact."

But the media coverage of the relationship in its early days unsettled sections of the British press and its readers.

Prince Harry even took the unprecedented step of issuing a public statement asking for privacy and describing some of the coverage as having "racial undertones".

Much was made of his fiancée's upbringing in Los Angeles, with the area described as gang-infested and a place riddled with racial tension.

However, Ms Markle actually grew up in a very middle class neighbourhood of Los Angeles and attended a private Catholic school.

But in many ways she is an outsider.

Prince Harry isn't following a traditional path - he's not marrying the daughter of a grand aristocratic family.

His wife-to-be now has to negotiate her way through the British aristocracy, in a similar vein to her future sister-in-law, the Duchess of Cambridge.

It is an experience American nutritionist and author Julie Montagu knows well, as the future Countess of Sandwich.

Born and brought up in Illinois, she married the son of the Earl of Sandwich and is now Viscountess Hinchingbrooke.

She splits her time between London and the family estate, Mapperton, in Dorset.

"Even now I still get things wrong," she told me. "The British upper classes have their own way of doing things. But as an American I bring my optimism, positivity and work ethic into the mix which I believe is hugely important."

Ms Markle is joining a family and entering a world unlike anything she has previously experienced. Yes it brings with it great privilege. But it also means a lack of privacy and the acceptance of a public life. As an actress she may find herself well equipped to deal with the scrutiny ahead.