To great laughter from the audience and the fun-loving royals, the beloved Australian character suddenly appeared in the royal box and sat down next to Charles and Camilla. Looking at her ticket, she joked, "I'm so sorry, they found me a better seat!"
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Charles and Camilla — who wore a specially-commissioned petrol blue Vivienne Westwood gown — had earlier walked the red carpet and greeted performers including Jesse J, Robbie Williams and West End composer Andrew Lloyd Webber.
They then took their seats to watch as the evening kicked off with a lively performance from Take That front man Gary Barlow, who sang Greatest Day and Let Me Go.
Liverpudlian comedian John Bishop was given the honour of hosting this year's Royal Variety Performance, which incorporates the best of British music, dance and comedy.
The evening included appearances from Jesse, who sang her latest single Thunder, the cast of musical Charlie and the Chocolate Factory, Mary J Blige, jazz musician Carol Emerald and Britain's Got Talent winners Attraction.
Choirmaster Gareth Malone's latest project, Voices, also performed, while Olly Murs sang a surprise duet with Robbie Williams — Jungle Book classic, I Wanna Be Like You.
The Royal Variety Performance will be screened on ITV on Monday 9 December.