The King attended the grand unveiling of the new main stage curtains at the Royal Opera House - crafted with a design in his honour.
Charles watched as more than 2,000 guests at the Covent Garden venue got a first glimpse of the curtains, which feature an embroidery of the King’s personal cipher.
The unveiling, along with an introduction by Sir Ian McKellen, began an evening of music and dance as performers took to the stage for the Spring Gala: Stories From The Royal Ballet And The Royal Opera.
The previous curtains had opened and closed on more than 10,000 performances since they were installed in 1997 and daily wear and tear meant it was time for a new set.
The mohair velour curtains each measure 9.75m wide and have a 10.8m drop.
The King’s cipher has been included to symbolise the enduring relationship between the monarchy and the arts, executives have said.
The monogram combines his initial “C” and “R” for Rex, the Latin for king, plus III as he is the third King Charles.
Alex Beard, the Royal Ballet and Opera chief executive, said it was “a privilege” to welcome Charles, who is patron of The Royal Ballet and The Royal Opera, to the gala which brought “together artists from both companies in a shared celebration.”
He added: “The unveiling of the new stage curtains marks an important moment for the organisation, reflecting our continued investment in the future of our stage and in the remarkable craft that underpins every performance.”
Earlier, Charles met representatives from curtain production specialists Gerriets and the expert embroiderers of the Royal School of Needlework, who helped create the new curtains.
He also viewed the original designs alongside intricate embroidery samples.
The new curtains were commissioned thanks to a grant from the Julia Rausing Trust, which supports excellence in the arts.
Charles went backstage after the show to meet the cast and get a closer look at the curtains.
Sir Ian plus Welsh Bass-baritone Sir Bryn Terfel and South African soprano Pretty Yende, who both sang in the show, were among those Charles spoke to.
Ms Yende, said it had been an “extraordinary night” and described the Royal Opera House as “one of the most extra ordinary opera houses in the world”.
She added “it is a singer’s dream” to perform there.
