Crown Princess Mary will become the first Australian to take the throne as queen after her mother-in-law announced she would abdicate in a shock announcement on New Year’s Eve.

Queen Margrethe of Denmark surprised the Danish people and the world when she revealed during her annual New Year’s Eve speech that she would abdicate on January 14.

Her eldest son, Crown Prince Frederik, will succeed her as King of Denmark, and his wife, Princess Mary, will sit next to him on the throne.

It will make her the first Australian-born queen in history.

Princess Mary, then known as Mary Donaldson, was 28 when she shook hands with the Danish prince for the first time at the Slip Inn bar during the 2000 Sydney Olympics.

The future King of Denmark was 32 years old at the time, and attended the Games to support his country’s sailing team.

Mary and Frederick

They dated long-distance for a year before Princess Mary moved to Copenhagen to study Danish.

The couple married in May 2004 and have four children – Prince Christian Waldemar Henry John, 18, Princess Isabella Henrietta Ingrid Margrethe, 16, and 12-year-old twins Princess Josephine Sofia Ivalo Matilda and Prince Vincent Frederik Minnick-Alexander.

Princess Mary often returns to her family home in Tasmania for the festive season, and was spotted at Sydney Airport on December 9 with Princess Josephine and Prince Vincent.

She also returned to Sydney in April for her first official tour of the country in more than a decade.

Her first act was to walk the two-kilometre bike path around the city’s famous Hyde Park alongside City of Sydney staff.

“It’s great to be here,” she told a Sunrise reporter who caught her just before she left.

She led a Danish delegation that discussed Australia’s transition to renewable energy, and visited Denmark-related construction and transport projects alongside the Danish minister for Development Cooperation and Global Climate Policy.