Letters and cards intimately written by Princess Diana to her family’s former housekeeper, are going to auction next week and are expected to fetch significant sums of money.

The letters were sent to Violet Collison, who the princess referred to as “Collie” during her childhood years at Park House, on the Sandringham Estate and they reveal that she remained in Diana’s thoughts throughout her life.

One of the letters, written on Buckingham Palace headed notepaper, was sent just three weeks before the Royal Wedding to Prince Charles, back in 1981.

Their friendship saw “Collie” send gifts to both her and Princes William and Harry, for which Diana responded with thank you letters, as well as regular Christmas cards.

They will go under the hammer in Stansted Mountfitchet, Essex, on 30 July and have already attracted a lot of interest from across the world, especially the United States.

Collie died in 2013, at the age of 89.

In service at Diana’s birth

Whilst in service at Park House, Ms Collison welcomed the births of Diana and her three siblings – Sarah, Jane and Charles. She had been the head housekeeper to John Spencer, Viscount Althrop, and his wife Frances Shand Kydd.

When the Spencer marriage broke down in 1967, she followed Diana’s mother to London, before returning to Norfolk to retire. Ms Collison continued to be close to Frances and all of the Spencer children right up to her death, in 2013.

Royal wedding letter

One double-sided letter, which has already been given an estimated selling price of around $1,200, was written on Buckingham Palace notepaper to Ms Collison and was thanking her for a birthday present.

However, the significance of this particular note is the date which is July 8, 1981 – just three weeks before the Royal Wedding.

She wrote: “Everyone frantically busy here doing last-minute decorations”, before the then Lady Diana Spencer ended the correspondence by reassuring her friend in saying: “The bride-to-be has remained quite calm!”

Ms Collison’s own personal invitation to the marriage with the then Prince Charles, is also amongst the set up for auction.

Brotherly love

Another letter dating back to September 1984, has Diana thanking “Collie” for a gift sent to Prince Harry. She wrote: “William adores his little brother and spends the entire time pouring an endless supply of hugs and kisses over Harry.”

That is a line that would probably embarrass both the Prince’s nowadays, following their highly publicised falling out and subsequent strained relationship. This note has also been given a provisional estimate of around $1,200.

Funeral invite

Several framed photographs and cards will be on offer, including a Christmas card from 1984 and quite poignantly there is a ticket for Diana’s funeral, for which the estimated sale price of $300 looks to be a great deal below what it will actually go for, considering its relevance.

Intimacy of letters evident

Sworders Fine Art Auctioneers are based at Stansted Mountfitchet in Essex, are understandably excited with the collection. Luke Macdonald, the Auction House director remarked how “intimate” the letters are.

“They’re things that otherwise we probably would not be aware of outside the small circles of the Royal family,” he said, before adding: “The fact that she was wanting to say a special thank you, for albeit small presents, really says how kind and generous and caring Diana was.”

Director reflects on relationship

Mr Macdonald confirmed that some of the individual letters had estimates of up to $1,200, but made the point that in all probability, given the Diana factor, they should fetch a good deal more.

“It would appear that Ms Collison was a constant in the princess’ life” he said, and reflected that there was obvious affection and she was possibly “somebody she could relate to and perhaps even escape from the world that she was in at the time… she adored her.”