A newly unveiled collection of Christmas cards and letters sent between Princess Diana and her parents’ housekeeper show their close bond over the years.

Violet Collison, affectionately known as ‘Collie’, worked for John Spencer and Frances Roche at Park House on the Sandringham Estate and witnessed the future Princess of Wales‘ birth.

Sweet handwritten thank-you notes and a decade of correspondence – which is being auctioned off next week – offer a glimpse into their friendship, including the late royal’s feelings ahead of her wedding.

Collie was a significant figure in Diana’s formative years and remained a close confidante even after she retired – even sending gifts to the young Princes William and Harry.

It would appear that their close relationship was largely a private one.

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Violet Collison, affectionately known as ‘Collie’, worked for John Spencer and Frances Roche at Park House on the Sandringham Estate and witnessed the future Princess of Wales ‘ birth. Diana pictured when she was young

Now, Collie’s family are selling the collection of cards, letters, photos and invitations at Sworders Auctioneers of Essex.

The 24 lots cover from 1979 through Diana’s wedding to Prince Charles and birth of her two sons in the 1980s, to the order of service for her funeral in 1997.

When the Spencers’ marriage ended, Collie worked for Diana’s mother Frances in London from 1967 until her retirement in 1973.

After retirement she lived in a bungalow near Sandringham, where Diana would often visit her secretly without her security detail.

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

One of the letters in the collection – penned on Buckingham Palace headed notepaper and dated just weeks before Charles and Diana’s wedding – is expected to fetch £1,200.

‘Everyone frantically busy here doing last minute decorations on the house and things like that,’ it reads.

‘Family all far too excited and, at the moment, the bride to be has remained quite calm!’

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Now, Collie’s family are selling the collection of cards, letters, photos and invitations at Sworders Auctioneers of Essex

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The 24 lots cover from 1979 through Diana’s wedding to Prince Charles and birth of her two sons in the 1980s, to the order of service for her funeral in 1997

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When the Spencers’ marriage ended, Collie worked for Diana’s mother Frances in London from 1967 until her retirement in 1973

Another from September 1984, also estimated at £1,200, describes the adorable relationship between a young Prince William and his new baby brother.

‘William adores his little brother and spends the entire time pouring an endless supply of hugs and kisses over Harry which is wonderful to watch if we are allowed near,’ Diana wrote.

Another sweet letter sees the late Princess thanking Collie for gifts sent to her young sons.

It said: ‘William found the parcels and dived into the paper before I could stop him.’ That letter is on Kensington Palace paper with a ‘CD’ logo for Charles and Diana – and also has an estimate of £1,200.

Luke Macdonald, head of art and estates at Sworders, said: ‘Violet Collison, Collie, was Diana’s parents’ housekeeper when they lived at Park House. She knew Diana from when she was born and remained a constant in her life.

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After retirement she lived in a bungalow near Sandringham, where Diana would often visit her secretly without her security detail

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Collie died in 2013 and the family has decided now is the time to sell them. Pictured, a thank you latter and a card

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A newly unveiled collection of Christmas cards and letters sent between Princess Diana and her parents’ housekeeper show their close bond over the years

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Collie was a significant figure in Diana’s formative years and remained a close confidante even after she retired – even sending gifts to the young Princes William and Harry. Diana and her sons pictured in 1995

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One of the letters in the collection – penned on Buckingham Palace headed notepaper and dated just weeks before Charles and Diana’s wedding – is expected to fetch £1,200

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The letters and cards will be sold in Stansted Mountfitchet, Essex, on July 30. A young Diana pictured in 1980

‘At all points she would try to return to see Collie. When she stayed at Sandringham she would escape to see Collie without her security.’

He expressed that they offer a ‘lovely chapter in the history of Diana’.

‘She was one of her closest confidantes,’ Luke continued. ‘They give a nice insight – before the wedding she describes everyone being frantically busy but the bride-to-be staying calm and there are letters about William and Harry that are really sweet.

‘Collie died in 2013 and the family has decided now is the time to sell them as they are just living in a box and not being enjoyed, there are too many family members to divide them up.

‘They have spoken to Diana’s sisters to make sure they were okay with them selling.

‘What is special about these is they tell a story, they are not just somebody’s collection. From the first Christmas card to the last, they are a complete story of her friendship and relationship with Diana.

‘Everyone wants a little part of Diana, she connected with people and was very much the people’s princess.’

The letters and cards will be sold in Stansted Mountfitchet, Essex, on July 30.