It was a classic Australian love story, set in a Sydney pub: Girl meets boy. Girl marries boy. Girl lives happily ever after.

But when Mary Donaldson, then a 28-year-old from Tasmania working in real estate, met “Fred” — also known as Frederik, Crown Prince of Denmark — at the Slip Inn in September 2000, she was suddenly plunged into an entirely different fairy tale.

“The first time that we met or shook hands, I did not know he was the crown prince of Denmark,” Mary said in a 2003 interview. “It was perhaps half an hour or so later that someone came up to me and said, ‘Do you know who these people are?’”

This month, more than 23 years later, Mary — now Crown Princess Mary, aged 51 — will become Denmark’s next queen, after Queen Margrethe II announced her abdication in her New Year’s Day speech. Mary’s husband will become King Frederik X.

She has become internationally acclaimed among royal watchers for her distinctive sense of personal style and her outspoken commitment to progressive causes, including climate change advocacy and sustainability, as well as the rights of women and children.

In Denmark, she is adored. And in her native Australia, the unlikely story of their Tasmanian princess has for decades prompted frothy headlines and extensive coverage of their homegrown member of the Danish royal family and her much-vaunted wardrobe.