[caption id="attachment_4720" align="alignleft" width="1600"] The historic abdication saw the passing of the Danish throne[/caption] Denmark has a new king following the historic abdication of the country's longest-reigning monarch Queen Margrethe II. The 83-year-old signed her parliamentary declaration handing the throne to her eldest son as thousands of people braved near-freezing temperatures to gather in central Copenhagen to demand the throne. King Frederik X is now the head of Europe's oldest monarchy. The former crown prince, 55, was then formally proclaimed king by the country's Prime Minister Mette Frederiksen on the balcony of Christiansborg Palace in the heart of the Danish capital. In his first speech as king, Frederik told the large cheering crowds: "My hope is to become a unifying king of tomorrow. "It is a task I have approached all my life. "It is a task I take on with pride, respect and joy." The king, who at one point was seen to wipe away a tear, was then joined on the balcony by his Australian-born wife Mary, 51, who is now queen, their children Christian, 18, who is the heir to the throne, Princess Isabelle, 16, and twins Princess Josephine and Prince Vincent, both 13. Karen Holk Jeppesen, 31, a communications consultant who had travelled to Copenhagen for the royal occasion, said: "It's very rare to witness a real historical moment that you know will be written about in the history books." Kasper Wiigh Larsen, 45, said: "It has really been worth it to stand here and wait all day." Unlike in the UK, there is no coronation ceremony in Denmark. King Charles and Queen Camila have sent their "very best wishes" to the royal couple. The King wrote: "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 also paid tribute to "the many years of service" of Frederik's mother. Margrethe stunned the nation of nearly six million on New Year's Eve when she announced her decision to abdicate after 52 years as queen, becoming the first Danish sovereign in nearly 900 years to do so. She cited health reasons having undergone major back surgery last February. Danish royal expert Thomas Larsen said: "The queen has been here and she has been on the throne for more than 50 years. And she is an extremely respected and popular figure, so people hadn't expected this and they were in shock."