The King has revealed his approach to birthday celebrations as he acknowledged his “advancing years” ahead of turning 76.

Charles wrote personally to thank the Military Wives Choirs for their gift of a new single in his honour, saying he was “deeply touched by your wonderfully thoughtful tribute”.

He expressed his “warmest possible gratitude for your very kind early birthday present” in the form of the choirs’ song, November Sunday, which was released last week.

The monarch added, in a nod to reaching a “certain age”: “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 none the less deeply touched by your wonderfully thoughtful tribute.”

The King also told how he experienced himself the “joy” of being in a choir at school and the bonds of friendship it nurtured.

And he praised the group for their steadfast support for loved ones who serve in the military, and for one another.

Charles reaches his 76th birthday on November 14 after a personally difficult year in which both he and the Princess of Wales were diagnosed with cancer.

November Sunday is a lullaby which reimagines the “chilly, foggy London night” a baby Prince Charles was born at Buckingham Palace in 1948, and the hope and joy of a recovering post-war Britain.

It is the chart-topping Military Wives Choirs’ first recording since 2020.

The King added: “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.”

He said his wife the Queen, who has been laid low with a chest infection, joined him in sending “all our blessings and kindest wishes”.

Camilla once revealed the King is particularly hard to buy birthday gifts for.

“I will tell you that he is the most difficult person in the world to buy a present for … So he likes to make a list of things that he wants so you get it exactly right,” she said.

He likes “a cake and a bit of a sing song”, she acknowledged, but admitted it was difficult to get her workaholic husband to take a break.

Caroline Paxton, chair of trustees at the Military Wives Choirs, said they were delighted to receive “such a thoughtful letter”.

“All of us at the Military Wives Choirs wish our King the happiest of birthdays,” she said.

“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.”

She added: “November Sunday is a heartfelt tribute, and we are delighted that His Majesty was touched by it.”

The Military Wives Choirs charity was launched following the BBC Two series with choral maestro Gareth Malone, and has grown into a network of some 70 choirs worldwide.

The organisation brings women in the military community together through singing, with a focus on wellbeing and resilience.

Some 100 singers, including serving personnel, wives, partners and veterans from 41 Military Wives Choirs across the UK and overseas, gathered to record the new track, which was released on November 1.

The song is now available to purchase or stream and the video can be found on YouTube or at militarywiveschoirs.org