Queen Camilla looked elegant in red as she welcomed the Amir of Qatar Sheikh Tamim bin Hamad Al Thani and his wife Sheikha Jawaher during the State Banquet.

Queen Camilla dons a stunning tiara at the State Banquet (Image: Ian vogler)

Queen Camilla looked elegant in a red velvet gown during the State Banquet at Buckingham Palace for the Qatar Royal Family this evening, as she attended despite her ongoing viral infection. The 77-year-old wore a glamorous ball gown, accessorised with some glittering jewels.

Tiaras are only worn by royals on rare occasions, with Queen Camilla and other women including Princess Kate only permitted to wear them during state banquets, white-tie events, royal weddings and coronations.

She wore a red velvet evening dress by Fiona Clare with the Diamond Kokoshnik tiara that belonged to the late Queen. The shape of this tiara unique and steeped in history.

It was orginally based on the traditional Russian headdress called a kokoshnik, which became very popular in Western Europe during the late nineteenth century. It boasts perfect matching diamonds in each of the 61 bars. The sparkling design is worth millions and estimated to be worth around £10 million.

Over the years it was work by Queen Mary and the late Queen on many occasions. Meanwhile, Queen Camilla accessorised with diamond earrings from her private collection, as well as a diamond necklace that also belonged to the late Queen and a ruby and diamond bracelet.

Queen Camilla donned a stunning red velvet state banquet (Image: Ian Vogler)

The Queen also wore the Family Orders of the King and the late monarch – which she wore at a white-tie event last month. The image featured a recent portrait of King Charles, 76 that was painted by miniaturist Elizabeth Meek MBE.

It has been a day jam-packed with engagements as the Royal Family greeted the Amir to Qatar Sheikh to the Horse Guards Parade following their flight to the UK on Monday. The ceremony was full of traditional pomp and pageantry. They received a warm Ceremonial Welcome before being formally welcomed by the King at the Royal Pavilion.

But Queen Camilla was absent from the lineup at Whitehall, as she was forced to pull out of the official open-air greeting due to the lingering effects of a nasty chest infection.

The Diamond Kokoshnik tiara that belonged to the late Queen (Image: PA)

The 77-year-old joined the royal party in the afternoon for a private lunch with the Amir and his wife where she revealed that her chest infection was a form of pneumonia.

It is understood that the Queen’s condition was viral, not bacterial, and she no longer has pneumonia. She was not taken to hospital with the condition but is now facing bouts of extreme tiredness.

The Queen was first diagnosed with the seasonal bug at the start of last month, following her long-haul trip to Australia and Samoa, and has reduced her diary on doctors’ advice.

Her medics have urged her to take time to rest and recover fully so it was advised that she avoid standing outside and travelling via carriage in the chilly temperatures.

Instead, she waited for the Amir and his wife inside the warm surroundings of the Grand Hall inside Buckingham Palace.

She was given the green light to attend tonight’s state banquet, though retired briefly after the official photographs were taken. But she will attend the dinner.