“Intimate” handwritten letters and cards from Princess Diana to her family’s former housekeeper are to be sold at auction.

The letters were sent to Violet Collison – who Diana knew simply as “Collie” – the housekeeper at Park House on the Sandringham Estate, where the princess spent her childhood years.

Collie remained close to Diana and sent gifts to both her and the princes, William and Harry, for which Diana responded with thank you letters and Christmas cards.

They are expected to sell for thousands of pounds when they go under the hammer in Stansted Mountfitchet on 30 July.

One of the letters, written on Buckingham Palace notepaper, was sent just three weeks before Diana’s wedding to Prince Charles.

“Everyone frantically busy here doing last-minute decorations,” the then Lady Diana Spencer observed, adding: “The bride-to-be has remained quite calm!”

In another letter from September 1984, Diana thanks her former housekeeper for a gift 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”.

Luke Macdonald, director at Sworders auctioneers, said the letters were “so intimate”.

“They’re things that otherwise we probably would not be aware of outside the small circles of the Royal family,” he added.

“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.”

Whilst in service at Park House, Violet Collison welcomed the births of Diana and her three siblings – Sarah, Jane and Charles.

After the Spencer’s marriage broke down, Violet followed Diana’s mother Frances Shand Kydd to London in 1967, before returning to Norfolk to retire.

“The lovely environment of Norfolk obviously held a very special place in her heart,” Mr Macdonald told the BBC.

“Diana would slip out under the radar without her security to visit Collie for a cup of tea.”

Ms Collison remained close to Frances and the Spencer children until her death at the age of 89 in 2013.

“She was a constant in Diana’s life, somebody she could relate to and perhaps even escape from the world she was in,” Mr Macdonald said.

“There was huge affection – she adored her.”

The auction house, based at Stansted Mountfitchet in Essex, said the Diana lots had attracted interest from across the world, especially the United States.

Also included are framed photographs and Christmas cards, as well as Ms Collison’s invitations to both Princess Diana’s wedding to Prince Charles in 1981, as well as her funeral in 1997.

Mr Macdonald said some of the individual letters had estimates of between £800 and £1,200, although he expected them to sell for more.

The lots will go under the hammer at Sworders Fine Art Auctioneers on Tuesday 30 July.

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