King Charles' "advancing years" mean he feels less of a need for birthday celebrations

According to the Daily Telegraph newspaper, Charles told the group he had been "deeply touched by your wonderfully thoughtful tribute".

He added: "While those of us of a certain age may feel the need for any such birthday celebrations is in inverse proportion to our advancing years, I am nonetheless deeply touched by your wonderfully thoughtful tribute."

The king also reflected on the "joy" he experienced as a member of a choir during his school days and thanked the group for their support for their loved ones in the military, as well as for one another.

He wrote: "I also wanted to thank you for your steadfast support not only for your loved ones serving in our military, who sacrifice so much time away from you and your families to protect us, but also for one another.

"Having sung in a choir myself when I was at school, I know the joy of performing together can create close-knit friendships and support groups, and I remain a firm believer that music has a unique power to unite and inspire us all."

Caroline Paxton, the chair of trustees at the Military Wives Choirs, admitted the group were delighted to receive "such a thoughtful letter".

She added: "All of us at the Military Wives Choirs wish our King the happiest of birthdays.

"With singers in our network ranging from 21 to 81, we wholeheartedly embrace the belief that age is just a number and not a constraint, with each passing year bringing new opportunity and possibility.

"At the heart of our charity is our commitment to community and mutual support, which we cultivate through the joy and unity of singing together.

"'November Sunday' is a heartfelt tribute, and we are delighted that His Majesty was touched by it."

The song features 100 singers from 41 Military Wives Choirs across the UK.