King Frederik X and his Australian-born wife Queen Mary have ascended the Danish throne. Here's how it unfolded

The ascension of King Frederik X and his Australian-born wife Queen Mary to the Danish throne was meant to be a lowkey affair.

But what they lacked in crowns and jewels, they made up for in joy and unity. 

Tens of thousands of people converged in Copenhagen, waving Danish and Australian flags, to herald a new era in the Scandinavian nation's history.

After more than five decades on the throne, Queen Margrethe II decided to abdicate in favour of her son, citing ill health.

Denmark started scaling back coronations in 1849, forgoing lavish ceremonies for a simple balcony proclamation. 

But Frederik was moved to tears when he saw the crowds that had gathered for his accession.

He paid tribute to his mother, and said he would need his wife Mary's support to be a "unifying king of tomorrow". 

These were the key moments from Copenhagen.

After giving her two weeks notice, Margrethe abdicated with the strike of a pen

Despite near-freezing temperatures, thousands of people lined the streets of Copenhagen to wave farewell to their beloved Queen Margrethe.

The 83-year-old, who became Europe's longest ruling monarch when her third cousin Queen Elizabeth II died in 2022, announced her decision to step down during her New Year's Eve address.

In keeping with the low-key, accessible "bicycle monarchy" she has built over the last five decades, Margrethe wanted a quick farewell with little pomp and ceremony.

She arrived at Christiansborg Palace in a horse and carriage, dressed in her trademark floor-length fur coat and a burgundy suit.

But her abdication was about as ostentatious as signing a couple of forms at the bank.

With her son, the new king by her side, Margrethe smiled as she signed the instrument of abdication. 

When she was done, she popped the lid back on her pen, stood up and motioned to her 18-year-old grandson, Crown Prince Christian, to bring her walking stick.

Then she stood smiling as she watched Frederik take her seat at the table.

Prince Christian, the new heir apparent, took his father's old seat to his right.

Fifty-two years after her father's death put her on the throne, Margrethe left on her own terms. 

Mary becomes Australia's first reigning queen 

In 2000, a handsome Dane caught the eye of 28-year-old Mary Donaldson at a Sydney pub called the Slip Inn.

"The first time that we shook hands, I did not know he was the crown prince of Denmark," Mary said in a 2003 interview with 60 Minutes Australia.

"It was perhaps half an hour or so later that someone came up to me and said, 'Do you know who these people are?'"

Two decades, one royal wedding and four children later, Mary is now the first Australian to officially crowned queen-consort.

Mary renounced her Australian citizenship to marry Frederik in 2004, and she speaks fluent Danish with just a hint of an accent.

Polls show Mary is a bit more popular with her subjects than her husband.

A survey by Denmark's public broadcaster DR found 79 per cent of Danes believe Frederik is ready to be king.

Meanwhile, 83 per cent said they think Mary is ready to become queen.

Frederik overwhelmed with emotion

Most Danes have never known a monarch other than Margrethe.

When she became queen in 1972, only 42 per cent of people were in favour of keeping the monarchy.

Over the past five decades, she has rebuilt the institution into one of the most popular and stable royal houses in Europe. 

Her son is now the custodian of the monarchy she saved. 

When he came onto the balcony of Christiansborg Palace and saw the huge crowd that had gathered for him, Frederik was overcome with emotion.

He wiped tears from his eyes as the Danish Prime Minister Mette Frederiksen proclaimed him the new king.

She turned in three directions, saying the words, "long live King Frederik X", to symbolise the new monarch's commitment to the whole of Denmark, including Greenland and the Faroe Islands.

Frederik then put on his glasses and gave a speech, promising his subjects to "become a unifying king of tomorrow".

"It's a task I've approached all my life. It's a task I've taken on with pride, respect and joy," he said.

Frederik also paid tribute to his mother, and said Margrethe would forever be remembered as an "extraordinary" regent.

The new royal family put on a show of solidarity

Frederik's ascension to the throne follows a tumultuous year for the Danish royal family.

Late last year, a Spanish magazine published photos of Frederik on an outing with Mexican socialite Genoveva Casanova in Madrid.

Ms Casanova has denied any romantic relationship with Frederik and threatened legal action against the magazine, while the Danish palace said they "do not comment on rumours or insinuations".

But on the day of his ascension, the king and his family presented a united front on the balcony of Christiansborg Palace.

After his proclamation, Frederik was joined by Mary, who was dressed in a white belted dress with a cape neck at the royal ceremony.

The outfit was designed by Soeren Le Schmidt and sewn by Birgit Hallstein, who also made Mary's wedding dress back in 2004.

The newly minted king and queen waved to the crowds before being joined by their four children.

Prince Christian is still in high school, though as the new heir apparent, he is likely to take on a more significant role in public life.

Princess Isabella is 16, and the twins Vincent and Josephine are 13.

Frederik and Mary wrapped their arms around each other and shared a kiss, much to the delight of the crowd, before retreating back into Christiansborg Palace.

The couple took a horse-drawn carriage back to their home Amalienborg, the official residence for the Danish royal family.

Back home and visibly more relaxed, Frederik and his family waved, hugged and kissed one more time for the crowds.

It is customary for each new sovereign to adopt a royal motto as a guiding principle for their reign.

Frederik chose: "United, committed, for the kingdom of Denmark."

The royal colours were then transferred from Margrethe's residence to her son's home, signalling that a new king is in the house.