
Europe's most glamorous royals assembled in Oslo to honour Norway's King Harald and Queen Sonja's 80th birthdays.

Members of the royal families from across the continent including the Countess of Wessex gathered at a gala dinner to commemorate the milestone event at the Royal Palace in the Norwegian capital.

Guest of honour Sophie, 52, was the belle of the ball in a sweeping emerald gown, while Queen Sonja opted for an eye-catching lime green number, topped with a dazzling tiara, as they made their way to the Palace.

Dressed in their brightest finery, the colourful royals made a grand entrance and were later seen on the balcony waving to well wishers - where one glamorous Belgian aristocrat unintentionally stole the show in a clinging red dress.

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The Countess of Wessex, 52, was the belle of the ball in a sweeping emerald gown as she joined a host of European royals (and Icelandic President Gudni Johannesson, pictured) in Oslo to honour Norway's King Harald and Queen Sonja's 80th birthdays

Desiree Kogevinas pulled a silly face as she joined Princess Sofia of Sweden, Prince Carl Philip, Crown Princess Victoria and Prince Daniel on the balcony

Belgian-born Desiree Kogevinas, the 39 year old daughter of Sweden's Countess Bernadotte and Nicos Eletherios Kogevinas, chose a red asymmetric gown for the event, but may have regretted her decision to go bra-less after stepping out onto the balcony for photographs on a brisk Spring evening in Oslo.

Something of an unfamiliar face among the likes of Sweden's Princess Sofia and Crown Princess Victoria, brunette Desiree, in a striking red dress topped off with a gold headpiece, still managed to ensure all eyes were on her.

WHO IS DESIREE, THE LADY IN RED? Born in 1977, Désirée Kogevinas is the daughter of King Harald's cousin, Madeleine Bernadotte, and her second husband, Nicolas Kogevin. A LinkedIn profile in her name suggests she studied French Literature at the Sorbonne before receiving a BA from Webster University. Ms Kogevinas is believed to have tied the knot with Justin Michael Oliver Rosenørn-Lanng in South Africa in 2008. She now lives in Geneva, Switzerland where she works for the International Trade Center, an organisation that supports small and medium-sized businesses. She is fluent in English, French, Greek, Spanish, basic Italian and Russian, according to LinkedIn. Advertisement

The Norwegian King and Queen both turn 80 this year and decided to mark the occasion with a joint celebration.

Queen Sonja was wearing a bright lime green gown with a red sash, and linked her husband's arm as they were led into the glittering celebrations marking their birthdays.

The royal couple were born just a few months apart and both looked remarkably youthful as they smiled for the cameras.

King Carl Gustaf of Sweden and Crown Princess Mette-Marit of Norway linked arms as they entered the celebrations and kept the colour to a minimum in comparison to the other royals in attendance.

Crown Princess Mette-Marit of Norway wore a sweeping white dress with embellished top and sleeves. She kept her blonde hair neat in a slicked-back up 'do and completed her outfit with dazzling drop earrings and a clutch bag.

Not one to be outdone, the perennially glamorous Grand Duchess Maria-Teresa of Luxembourg arrived with King Willem-Alexander of the Netherlands, and kept her floor-length black dress concealed with a long blush pink coat.

She wore a sparkling tiara which complimented her outfit and also kept a tight grasp of King Willem-Alexander as they entered the room.

Prince Albert of Monaco and Crown Princess Mary of Denmark made an appearance for the royal couple's joint celebrations

An official photo released by Norway's Royal Court shows King Harald and Queen Sonja celebrating their 80th Birthdays surrounded by members of their family

Norway's King Harald and Queen Sonja arrive at a gala dinner to celebrate their 80th birthdays on Tuesday night. The birthday Queen wore a striking line-green number complete with a dazzling tiara and a shimmering silver clutch

Left to right: First Lady of Finland Jenni Haukio, Desiree Kogevinas, Carlos Eugster, Crown Princess Victoria of Sweden and Prince Daniel of Sweden greet the audience from the balcony of the Royal Palace

King Carl Gustaf of Sweden and Crown Princess Mette-Marit of Norway link arms as they enter the palace's celebrations. The Norwegian Princess looked stunning in a sweeping white gown with colourful floral detail around the collar

A royal runway show! Crown Prince Pavlos of Greece and Jenni Haukio, wife of Finland's President Sauli Niinisto enter (left) followed by King Philippe of Belgium and Princess Martha Louise of Norway (right)

King Willem-Alexander of the Netherlands and Grand Duchess Maria-Teresa of Luxembourg smile as they walk arm in arm. The Dutch King's wife Maxima was also in attendance, but she entered the ballroom separately

CROWN PRINCE OF PRANKS! HAAKON OF NORWAY BAFFLES GUESTS BY SHAVING OFF HIS BEARD DURING GALA DINNER Before and after: Crown Prince Haakon of Norway shaved off his beard in a bizarre prank during the King and Queen's joint 80th birthday celebrations Crown Prince Haakon of Norway shaved off his beard in a bizarre prank during the King and Queen's joint 80th birthday celebrations. The mischievous prince left diners scratching their heads after sneaking off for a shave during a gala dinner in honour of his parents, King Harald and Queen Sonja, at the Royal Palace in Oslo. The 43-year-old prankster was joined by Europe's most glamorous royals at the regal event, including the Countess of Wessex. King Harald celebrated his birthday on February 21, while Queen Sonja will reach the milestone on July 4. Further celebrations marking the couple's birthdays include a reception thrown by the King and Queen on their royal yacht, the Norge. At the end of the week the Royal Guard will then march from the palace through the city to the Oslo Opera House and festivities will end with a fireworks display. Advertisement

Crown Princess Mary of Denmark accentuated her figure in a floor length patterned pink dress with nipped in waist. She kept her dark tresses in a simple up do but finished off her look with a dazzling tiara and sparkling pink clutch bag.

Also at the celebrations was Queen Maxima, who matched her outfit perfectly with her accessories. However the Dutch royal, who is known for her colourful outfit choices, opted for a more toned-down look that normal.

The blonde royal wore a floor length nude dress covered with blue flowers and kept her jewellery, which included earrings, brooch and a tiara, the same diamond design.

The stylish Danish royal made a bold sartorial statement, choosing a peplum skirt instead of a traditional full gown

Grand Duke Henri of Luxembourg and Queen Maxima arrive, with the blonde royal wearing matching diamonds and tiara

Crown Prince Haakon of Norway leads Queen Margrethe of Denmark wearing a floor length turquoise dress

Queen Anne-Marie of Greece, left, and Princess Mabel of Oranje-Nassau from the Netherlands, right arrive at the Royal Palace

Finland's President Sauli Niinisto and Queen Silvia of Sweden (left), closely followed by Prince Carl Philip of Sweden and Queen Mathilde of Belgium (right) were among the glamorous royal guests at the dazzling gala dinner

Crown Princess Marie Chantal of Greece, right, and Lady Elizabeth Shakerly of Great Britain make a stylish arrival

Princess Tatiana of Greece and Denmark (left), princess Sofia of Sweden and Bernhard Mach (C) attend to the gala dinner as part of celebrations

Left to right: Carlos Augster, Hereditary Grand Duchess Stephanie of Luxembourg and Prince Constantijn of the Netherlands

Crown Prince Frederik of Denmark and Princess Beatrix of the Netherlands arrive together at the gala dinner

Queen Margrethe of Denmark wowed in a turquoise blue dress and laughed as she linked arms with Crown Prince Haakon of Norway.

The 77-year-old royal sparkled in her gown and completed her look with white heels, bag and a pearl necklace.

After the celebrations, the King and Queen of Norway decided to take to the balcony to wave at well wishers who had gathered to help celebrate the royal couple's joint birthdays.

The rest of the royals joined on another part of the balcony and smiled as they looked on at the crowds which had gathered before them.

Queen Sonja and King Harald greet well wishers from the balcony of the Royal Palace in Oslo

Iceland's first lady Eliza Reid, Iceland's president Gudni Johannesson, Grand Duchess Maria Teresa of Luxembourg, Prince Albert II of Monaco, Grand Duke Henri of Luxembourg, Queen Mathilde of Belgium and King Philippe of Belgium look on at the crowds who have gathered

Leah Isadora Behn, Princess Ingrid Alexandra, Prince Sverre Magnus, Maud Angelica Behn, Queen Sonja, Emma Tallulah Behn, King Harald, Crown Princess Mette-Marit, Crown Prince Haakon and Martha smile at the well wishers below

Crown princess Mette Marit of Norway (L) and Crown Prince Haakon of Norway smiled as they looked at the onlookers

Queen Maxima, in the middle, blew her nose as the rest of the royals looked on at the spectators below

Queen Sonja and King Harald join Princess Emma Tallulah Behn, Crown Princess Mette-Marit, Crown Prince Haakon and Princess Martha Louise

King Willem-Alexander, Queen Maxima, Princess Beatrix, Princess Mabel, Prince Constantijn and Princess Astrid looked engrossed in a piece of paper on the balcony

The royals smiled broadly as they waved to the crowds below who had gathered to join in with the joint birthday celebrations

The women all wrapped up for the cold weather and their glistening tiaras were hard to miss as they stood on the balcony together

Crown Princess Victoria dazzled in a bright blue dress as she stood with Prince Daniel King on the balcony

Princess Emma Tallulah Behn, King Harald, Crown Princess Mette-Marit, Crown Prince Haakon and Princess Martha Louise smiled together

Prince Constantijn and Princess Mabel stood just behind the beauty flower arrangement on the balcony railings

Sophie Countess of Wessex, Queen Silvia, King Carl Gustaf, King Willem-Alexander, Queen Maxima, Princess Beatrix, Princess Mabel, Prince Constantijn and Princess Astrid

The royals clapped as King Harald and Queen Sonja took to the balcony to greet the crowds and celebrate their birthdays

The royals smiled and waved as they stood waiting for the King and Queen to arrive and join in with the celebrations

Despite looking as though they were cold, King Willem-Alexander, Queen Maxima, Princess Beatrix, Princess Mabel, Prince Constantijn and Princess Astrid smiled

They continued waving and showing their appreciation for the crowds of people who had turned up for the special occasion

There were so many people there for the joint birthdays that they took up the entirety of the long balcony at the palace

King Harald gives a speech to his royal guests (left: wife Queen Sonja and right, Queen Margrethe II of Denmark)

King Harald turned 80 on February 21st this year, while Queen Sonja will reach the milestone on July 4th.

This isn't the only event for both royal guests and the public this week to mark the couple's joint birthday; tomorrow, the King and Queen will host guests on their royal yacht the Norge.

The Royal Guarde will then march from the palace through the city to the Oslo Opera House, and celebrations are set to end there with fireworks.