The King made a solo appearance at the Gladiator II premiere in London on Wednesday, after the Queen pulled out to aid her recovery from her chest infection.
While none of the other royals stepped in for Camilla last-minute to rub shoulders with the star-studded cast, many fans may be wondering who the King's mystery companion was as he arrived by car at the ODEON in Leicester Square.
The woman pictured in the back of the car with the monarch is believed to be the King's Assistant Private Secretary, who works alongside Their Majesties' principal Private Secretary, Sir Clive Alderton, who has worked with Charles and Camilla since 2015.
According to the royal household's website: "The Private Secretary's Office acts as the primary source of advice to His Majesty The King in his role as Head of state and Head of Nation.
"Advice relates to constitutional, governmental and political affairs, including those affecting the 14 realms in which His Majesty is Head of State and in the 54 countries of the Commonwealth of which The King is Head.
© Getty"It is also responsible for policy guidance on matters concerning The King's role in relation to the Church of England and the Church of Scotland."
The King's night out at the premiere came on the eve of his 76th birthday, but it was business as usual for His Majesty.
On Thursday, Charles opened the first two Coronation Food Hubs, in-person at Deptford in south-east London and virtually in Knowsley in Merseyside.
The King was presented with a homemade birthday card by a group of schoolchildren who also sang to him.
© GettyCharles also attended a "surplus food festival", which showcased meals created from food that would otherwise have gone to waste.
He sat down with a group of children from Peckham's Rye Oak Primary School who will benefit from the new hub, and listened to them talk about the foods they like, asking about their school lunches.
Asked if he would be putting his feet up for his birthday, he said: "Not quite."
