Debonair, well heeled and charming, Chris O'Neill has been described by Queen Silvia of Sweden as "every mother-in-law's dream". Her daughter Madeleine, her youngest child with King Carl Gustaf, called him simply "my soul mate".

A soul mate wasn't, perhaps, what the pretty European royal was looking for when she moved to New York in 2010 with a shattered heart – she'd just ended an engagement to her boyfriend of eight years after reports of his infidelity.

But a soul mate is what she found in the US financier, who is a partner with the hedge fund Noster Capital, giving advice to wealthy clients.

Remembering their first meeting via mutual friends, she told her countrymen "it started with a great friendship". "We share the same humour and we have a lot of fun together. Christopher opened up my heart."

The lovestruck princess added that he has "very big heart" and "manages to make everyone in his presence feel good".

Her Prince Charming was equally effusive, saying: "From the very outset, I immediately felt something special with Madeleine."

Born in London on June 27, 1974, he is the son of late investment banker Paul O'Neill and his wife Eva, a German socialite and philanthropist, who mingles with royalty. (She is friendly with Prince Charles).

He attended boarding school at the Institut auf dem Roseberg in Switzerland, before moving to his father's country to study at Boston University and the Big Apple's Columbia Business School.

This international background and his European roots – he is to this day a Chelsea football fan – appealed to the princess, who also lived for a time in London and whose mother is German and Brazilian.

By February 2012, the couple had moved in together, and by the following May it was clear he'd been welcomed into the royal family.

With the express permission of her father, he attended the christening of Estelle, the daughter of Madeleine's sister Crown Princess Victoria, in presence of a plethora of European royalty.

A few months later, the dashing American was asking the king for her hand in marriage.

Their union could make him the Duke of Hälsingland and Gästrikland, if he takes his wife's titles. But first Chris would have to become a Swedish citizen ahead of their wedding in 2013.