Princess Anne and Sophie missed fun party at Clarence House which Kate left at midnight

Many members of the Royal Family attended, including the Prince and Princess of Wales, Queen Camilla, and Princess Beatrice.

However, the King's sister Princess Anne, his brother Prince Edward, and the Duchess of Edinburgh did not attend.

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The Princess Royal's reason was because she attended engagements in Glasgow on Tuesday.

She concluded the day by making an appearance at the Scottish Interfaith Week Forum.

Meanwhile, the Duke of Edinburgh, the King's younger brother, could not attend the birthday party as he landed in Singapore that day.

Prince Edward, 59, visited SwissŠtel the Stamford for the Commonwealth Games Federation reception.

On the evening of King Charles's birthday party, Sophie, Duchess of Edinburgh, 58, went out for a meal at Rochester Cathedral.

It is not known whether or not the Duke of York, who withdrew from public life in 2019, was present at Clarence House.

In a tribute to her former brother-in-law, Sarah, Duchess of York, the ex-wife of Prince Andrew, shared a black and white photo of a young Charles on Instagram.

Fergie, 64, captioned the post: "Wishing the happiest of birthdays to His Majesty, King Charles III. Long live the King."

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Princess Kate, 41, looked very elegant at King Charles's birthday party, wearing a Needle & Thread Alicia Scallop gown in emerald.

Meanwhile, Princess Beatrice, 35, looked gorgeous in a Monique Lhuillier Sequined Stretch-Tulle midi dress in metallic rose gold with a matching capelette.

The King's niece, Zara Tindall, 42, also attended and wore a Rebecca Vallance "Eva" cut-out detail midi dress in black.