Revealed at last: Princess Diana's most discreet confidant who she affectionately nicknamed 'Collie'

After Princess Diana's tragic death, many have chronicled her life in works of fact and fiction. 

But none has revealed the identity of one of her closest confidantes, Violet Collison, whom she affectionately called 'Collie'.

'A number of times she was asked to contribute to various books, and she just flatly refused,' a relative of Collie tells me.

As head housekeeper to Diana's parents at Park House on the Sandringham estate, Collie had been a significant figure in Diana's formative years. 

One of Princess Diana's closest confidantes was Violet Collison, whom she affectionately called 'Collie'

Pictured: An envelope addressed to 'Mrs V Collinson' at 5 Bradfield Close, North Walsham in Norfolk, in December 1984

In her letter dated December 13 1984, Diana thanks Collie for Christmas presents bought for her sons Prince William and Harry

As head housekeeper to Diana's parents at Park House on the Sandringham estate, Collie had been a significant figure in Diana's formative years

The bond remained strong until the fatal car accident that took Diana's life in 1997.

Only now, more than a decade since Collie's death in 2013, is her relationship with the princess coming to light, as unseen letters go up for auction at Sworders at the end of this month.

'Collie and Diana had this relationship until she died that goes over and beyond what a housekeeper would normally experience,' the relative tells me.

Diana's difficult relationship with her mother is well-documented. There were periods when they would not be in contact, while Collie was a constant.

'When Diana and Charles were staying at Sandringham,' the family member explains, Diana 'used to try and escape — I think one of her boltholes was a little two-bedroom bungalow in a village two miles down the road [Collie's home]'.

While Diana had a difficult relationship with her mother, Collie remained a constant contact

Diana with her son, Prince William. The Princess's visits to Collie's home were kept secret and she would go without any security staff

These visits were kept secret, and Diana would go without any security staff.

In retirement, Collie worked part-time at the Sandringham ticket office.

One day royal biographer Penny Junor came snooping, the family member reveals.

'When Penny asked at the ticket office if anyone knew a 'Collie', the lady working behind the counter said no . . . that person was Collie.'