It’s been described as “an extraordinary and historic event”.

For the first time in 900 years, the head of the Danish royal family, HM Queen Margrethe 11 will abdicate on January 14, paving the way for her son, Crown Prince Frederik, 55, to ascend the throne as King and Australian-born Crown Princess Mary, 51, to be Queen.

A popular Danish royal since her fairy-tale romance, which started when she met Fred at a pub during the Sydney 2000 Olympics, Mary will also make history, becoming the first Australian to head a European royal family.

With Danish flags already flying over the streets of the capital Copenhagen, the Queen, the Crown Prince couple and their eldest son, Prince Christian, will arrive at Christiansborg Palace just after 1.30pm local time on Sunday (11.30pm AEDT) for the big handover.

The official succession takes place inside the palace and by 3pm Prime Minister Mette Frederiksen will declare His Majesty King Frederik X and Queen Mary’s accession to the throne on the palace balcony.

By all accounts, it will be a much more low-key affair compared to the global spectacle surrounding the British monarch’s coronation of King Charles in May last year with no world leaders and dignitaries expected to be involved in the succession ceremonies.

According to author and palace expert Thomas Larsen, Danes are expected to embrace the generational change after Margrette’s 51-year reign.

‘A splendid Queen’

”She’ll be a splendid Queen,” says Søren Ravn Jensen, the director of one of Mary’s 32 patronages.

Danes are expected to embrace the generational change, according to author and palace expert Thomas Larsen, who says the royal couple have a public approval rating of about 85 per cent.

”They should not try to be a cheap copy of [Margrethe]. They have to find their own path,” he says, attributing much of Mary’s popularity to her mastery of one of Europe’s most difficult languages.

”The key to making a close relationship with Danes is to be able to speak the language,” he said, adding the public never quite warmed to the Queen’s French-born late husband Prince Henrik, who struggled to gain fluency.

Strøget, the central shopping street in Copenhagen decorated with Danish flags ahead of the change of throne in Denmark. Photo: Getty

How succession day will unfold

On Sunday at 1.35pm, the Crown Prince couple and Prince Christian ride in a motor car from Frederik VIII’s Palace, Amalienborg to Christiansborg Palace, according to the official palace website .

Two minutes later, at 1.37pm, the Queen rides in a carriage from Christian IX’s Palace, Amalienborg to Christiansborg Palace, escorted by the Guard Hussar Regiment.

At 2pm, the Queen, the Crown Prince and Prince Christian participate together with the Government and the Council of State secretary in the Council of State.

The succession of the throne takes place during the Council of State meeting at the moment when the much-loved Queen Margrethe, 83, has signed a declaration of her abdication.

At 2.15pm, Queen Margrethe leaves Christiansborg Palace and rides in a motor car to Christian IX’s Palace, Amalienborg.

The Golden Carriage will escort the Queen to the palace for the succession handover and return with the new King and Queen. Photo: Getty

At 2.30pm, the King and Queen “hold a levee [reception]” for special guests and at 3pm His Majesty King Frederik X and Her Majesty Queen Mary step out onto the balcony of Christiansborg Palace with the prime minister.

He then publicly proclaims His Majesty’s accession to the throne and Fred will briefly speak to his new subjects.

At 3.30pm, Fred and Mary ride in the golden carriage, escorted by the Guard Hussar Regiment’s mounted squadron, from Christiansborg Palace to Frederik VIII’s Palace, Amalienborg.

And that’s about it for official duties.

The next day, there’s a reception in the Danish parliament followed by a reception in the former Upper Chamber.

Mary at the opening ceremony of the exhibition Fashioned From Nature at the Danish Natural History Museum. Photo: Getty

What does Mary’s future look like as Queen?

As part of Mary’s promotion, she is expected to take on several high-ranking patronages once the royal household finishes a review and redistribution process.

”There are high-ranking patronages that more or less belong to the Queen. Some of them at least will be transferred to her and Frederik,” says Copenhagen University historian Sebastian Olden-Jørgensen.

Empowering women and girls, mental health, the environment and sustainable fashion are among some of the causes she has championed over the years.

”She has been trying to make a difference and use her position within the royal family to improve the lives of others,” adds Larson.

Her Mary Foundation has focused on combating domestic violence and school bullying.

Princess Mary tours the Nordic Museum in Seattle, Washington. Photo: Getty

Denmark’s ‘biggest influencer’

Mary has graced the cover of Denmark’s top women’s magazine, ALT for damerne, several times and editor-in-chief Rikke Dal Støttrup said that from day one she has been an ”icon for Danish women”.

She has a special ability to effortlessly carry both long gowns with trains for gala events and jeans and sneakers with natural ease, Støttrup said.

”We immediately connected to her style, which was both classically elegant and contemporary at the same time.

”In a way, she can be considered the country’s biggest influencer.”

Although she faced a steep learning curve to become a royal, Copenhagen University historian Sebastian Olden-Jørgensen expects Mary to make a smooth transition to Queen.

”She will continue very much as she is … serious. (Fred) is the one who has to change,” Olden-Jørgensen said.

”He’s very down to earth … he will have to learn to exercise a bit more dignity and distance”.

Crown Princess Mary in Hobart with her family Prince Vincent, Prince Christian, Crown Prince Frederik, Princess Josephine, Princess Isabella. Photo: Instagram/Danish Royal Family

Royal commentators say one of Mary’s most significant roles in the Danish royal household has been to help her husband feel more at ease in the spotlight and shake off his party-boy past.

”He has certainly settled down and become increasingly comfortable with his role as a royal. Well into his 30s, it was evident that he was uncomfortable with being the centre of public interest,” Olden-Jørgensen said.

”His mother the Queen said in a speech once … ‘When Mary entered your life we could see spring around you suddenly, we could see you had found your life companion’,” Larsen added.

‘Once is never’

The royal couple’s marriage has been the subject of intense tabloid media speculation in recent months following the publication of pictures of the crown prince and a Mexican socialite on a night out in Madrid.

But the Danish public’s response was: ”Once is never, but twice is a bad habit,” Olden-Jørgensen said.

”If this stays an isolated incident people will forgive and forget but if he continues with something like that, he will cause serious trouble for himself and the monarchy,” he said.

Besides Christian, Fred and Mary’ have three more children – Princess Isabella, 16, and twins Prince Vincent and Princess Josephine, who turn 13 on Monday.

”Mary has shown herself as a true professional and has been a good teacher,” Olden-Jørgensen said.

”The greatest asset of the royal couple is their children, they are well-behaved and charismatic. Family values are very important to the success and identity of the Danish monarchy.”

“To Danes, royalty is about family.”