King Charles and Queen Camilla have sent a personal message to King Frederik and his wife Queen Mary on the day of their accession to the throne.
In a message shared by Buckingham Palace, Charles, 75, and Camilla, 76, sent their "very best wishes" to Denmark's new king and queen, whilst also paying tribute to Frederik's mother, Queen Margrethe II - Europe's longest-reigning monarch.
Crown Prince Frederik, 55, only learned of his mother's plans to abdicate just three days before her surprise announcement on 31st December in her New Year address.
A spokesperson from the royal palace confirmed to Danish newspaper Berlingske that the queen informed both her sons, Crown Prince Frederik and Prince Joachim, about her decision to abdicate on 28 December.
In his letter, Charles wrote: "My wife joins me in writing to convey our very best wishes on the day of your accession to the throne of the Kingdom of Denmark. I look forward to working with you on ensuring that the enduring bond between our countries, and our families, remains strong, and to working together with you on issues which matter so much for our countries and the wider world."
He continued: "I pay tribute to the many years of service of your mother, Her Majesty Queen Magrethe II, and remember fondly the frequent visits between our countries, including our visit to Copenhagen and Elsinore in 2012. I was delighted that Your Majesties were able to attend our coronation last year and I much look forward to future opportunities to celebrate the close connection that unites our countries and our families."
The historic day is set to continue this afternoon at 5pm local time with a transfer of the royal flags from Christian IX's Palace to Frederik VIII's Palace at Amalienborg, where Frederik and Mary reside.
The Danish royal palace has confirmed that Margrethe will still be known as Her Majesty Queen Margrethe. Her abdication in her New Year's address came as a complete surprise for many.
Announcing her decision to step down, she said in her address: "In February this year I underwent extensive back surgery. It went well, thanks to the skilled healthcare staff who took care of me. Of course, the operation also gave rise to thinking about the future - whether the time had come to leave the responsibility to the next generation.
"I have decided that now is the right time. On 14 January 2024 – 52 years after I succeeded my beloved father – I will step down as Queen of Denmark. I leave the throne to my son Crown Prince Frederik."