The Duchess of Cornwall has a "wonderful experience" at BBC Radio 5 Live

Twitter account @GertsRoyals shared a thank you letter sent by the duchess after the fan took her time to praise her appearance on the show and send birthday wishes.

Camilla wrote in the letter: "Dear Gertrude, Thank you for your kind letter about my recent Guest Edit of the Emma Barnett Show. I am so glad you enjoyed the programme.

"It was a wonderful experience, and I was delighted that so many of my charities, including SafeLives, were able to participate."

Camilla went on to send her best wishes to the fan during the "challenging time" of the coronavirus pandemic.

She wrote: "I do hope you and your family have been safe and well during this challenging time. With best wishes, Camilla."

The note was accompanied by a photo of Camilla, who posed on the steps of her Scottish home Birkhall in jeans and a blue sweater over a pink shirt while reading 'All Change' by Elizabeth Jane Howard.

During her appearance on BBC Radio 5 Live, Camilla compared her 71-year-old husband to a "mountain goat" and said he was the "fittest" man of his age that she knows.

She said: "He is probably the fittest man of his age I know. He'll walk and walk and walk. He's like a mountain goat - he leaves everybody miles behind."

The duchess also admitted she used to "hate" the internet but the lockdown measures put in place due to the coronavirus pandemic has changed her attitude because it has provided her with a vital lifeline to stay in touch with her family.

She said: "I'm ashamed to say that I really hated the internet. I didn't understand it and I thought, 'What's the point of this?'.

"Since lockdown, it's been so brilliant because I've been able to communicate with family, my children, my friends.

"But it's also taught children ... otherwise children who aren't at school what would they have done without it?"