Touching private letters from the royal family to a trusted servant, including notes from the Prince of Wales expressing his personal feelings about major life events and a controversial television appearance, are to be auctioned.

The large collection belonged to Marjorie Dawson, who served as personal dresser and maid to the Queen’s cousin Princess Alexandra for 36 years before retiring in 1990.

Among the many letters are those from heir to the throne Charles expressing his joy at the birth of Prince William, sorrow at the death of his grandmother the Queen Mother, and his delight at marrying Camilla Parker Bowles, now the Duchess of Cornwall.

But he also wrote to Ms Dawson after she contacted him when he took part in a 1994 documentary with biographer Jonathan Dimbleby and admitted adultery on national television.

The prince described his own appearance in “that television programme” as “living dangerously”.

Charles wrote: “I was enormously grateful for your very kind letter following that television programme the other day.

“I suspect it was what is called ‘living dangerously’, but it seems difficult to avoid nowadays!”

He added: “I’m glad you enjoyed it and managed to remain fully awake for two and a half hours!”

After his 2005 wedding to Camilla, with whom the prince had an affair while married to the Princess of Wales, he wrote to Ms Dawson: “And you can have no idea how lucky I am to have my Darling Camilla.”

In another note, the prince, responding to a letter ahead of his high-profile wedding to Diana in 1981, urged Ms Dawson – who was invited to the nuptials – to use the loo before taking her seat.

The prince wrote: “I am so touched that there was such a nice reaction to your wedding invitation.

“I couldn’t be more delighted that it has given so many people such pleasure.

“Don’t forget to go to the loo before the wedding – it could be a very long wait in the cathedral! With my love, Charles.”

In other letters, the prince described his concern over the press, saying: “Unfortunately, we are now to be treated as mere pawns in a terrifying & ongoing media circulation war where the actual facts are totally disregarded & vast sums of money are offered as bribes to former, & current, members of staff.”

Following the death of his grandmother the Queen Mother, Ms Dawson contacted him with her condolences and the prince wrote, on black-edged mourning paper, how he “dreaded her eventual departure” and that there was “an enormous chasm in my life”.

But he added: “She also leaves behind the most wonderful legacy of unbelievably happy memories of fun, laughter and an atmosphere of constant affection and interest in everything.”

After William’s birth in 1982, Charles wrote how he and Diana were “rapidly discovering what it is to be proud parents!”.

Ms Dawson’s family uncovered the carefully collected memorabilia, which includes dozens of Christmas and birthday cards, invitations and notes, following her death at the age of 104 in 2019.

Among the items was a handwritten thank you note from Princess Anne, now the Princess Royal, in 1968 signed “love Anne” which said: “Many thanks for looking after me so well, kindly and patiently… I don’t know what I would have done without you.”

In another letter, the Queen Mother told Ms Dawson, after a stay in hospital: “Now I feel perfectly well, just as if nothing had happened”.

Ms Dawson’s great-cousin David Knibb, 69, from Jersey said: “Marjorie married later in life to a royal butler, Willoughby Wood Barnard, but it was a single person’s job.

“She never had any children. It’s been a long process sorting through all the memorabilia.

“We’ve found Easter messages from the Queen Mother and a letter from Princess Alexandra saying she missed Marjorie when she was on holiday.

“This is just the tip of the iceberg. There are five diaries each documenting five years of royal service and we’ve found cine film and slides in the attic.”

He added: “Marjorie claimed the secret of her long and successful life was a regular glass of whisky and portion of fish and chips. Perhaps that’s why the royals liked her so much.”

Jim Spencer, Hansons’ paper expert, described the memorabilia as significant and intriguing and said he spent a number of late nights examining the packets and piles of paper.

“This is such an important collection, much of it untouched. Marjorie must have cherished her career because she kept every little thing,” Mr Spencer said.

“I found envelopes stuffed full of postcards, programmes, menus, brochures, and countless notes on headed paper from houses, castles and palaces around the world.”

He added: “She was clearly a steadfast, treasured, loyal and devoted royal servant who gained the affection of the family she served.”

The items, which are being sold online in 81 lots by Hansons Auctioneers on October 13, are expected to fetch more than £10,000 in total.

Ms Dawson, who grew up in Bolton and was orphaned at the age of 12, was awarded the Royal Victorian Medal for her service to the royal family.