King Charles offers "best wishes" to Denmark's new king and queen
King Frederik X took the throne after his mother abdicated from the role
King Charles and Queen Camilla have given their "very best wishes" to Denmark's new king and queen as they ascend to the throne.
King Frederik X and Queen Mary came to be the new prime royal members after Frederik's mother Margrethe abdicated from her position as Queen.
Taking to social media, King Charles wrote a message, which was published by Buckingham Palace, to wish the new king and queen the best for their reign.
He also paid tribute to "the many years of service" Margrethe gave to her country, as she recently became Europe's longest-reigning monarch after the passing of Queen Elizabeth II.
Margrethe chose to leave the position as she addressed the nation in her annual New Year's address to the Danish public.
She admitted that she had had "thoughts about the future" which had triggered her to consider abdication, which were only heightened when she had important surgery to her back.
The Danish crown now passes to 83-year-old Margrethe's 55-year-old son Frederik, as British King Charles has written privately to the outgoing monarch.
In a separate letter to the new royal couple, Charles and Queen Camilla wished Frederik and Mary the best of luck in their reign of the kingdom.
"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," they said.
"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.
"I pay tribute to the many years of service of your mother, Her Majesty Queen Margrethe 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."