To Prince Charles, the Queen Mother was far more than just a grandmother.
From his earliest years, she was a constant, guiding force in his life. She acted as his counsellor, confidante and mentor, advising him in both private and state matters, reports the Daily Mail.
The prince, 68, has spoken openly of his affection for his 'magical' grandmother, with whom he once said he enjoyed his closest family relationship.
The feeling was mutual. The love the Queen Mother felt for her grandson is revealed in a series of personal letters to be aired on tonight's episode of The Royal House of Windsor, a revealing six-part series about the rise of Britain's royal family.
One historian claimed he found in his 'huggable' grandmother the warmth and affection that was missing from his relationship with his own 'distant'.
Dr Piers Brendon, author of The Windsors: A dynasty revealed, said: "The Queen Mother was huggability personified, she was tremendously affectionate, and welcoming and warm and cuddly.Whereas the Queen was a very distant mother."
During the first years of his life, Charles often found himself in the care of his grandmother and grandfather, King George VI.
When the Queen and Prince Philip embarked on their six-month tour of the Commonwealth in 1953, Charles and Anne stayed with the Queen Mother.
When Charles and Anne left to join their parents in Tabruck, North Africa, the Queen Mother wrote ahead to her daughter to extol her grandson's virtues.
"You may find Charles much older in a very endearing way," she wrote in March 1954. 'He is intensely affectionate. And loves you and Philip most tenderly.
"I am sure that he will always be a very loving and enjoyable child to you both."
The Queen Mother also championed Charles when it came to choosing a school for the young prince.
She wanted her grandson enroll at Eton, where he could remain close to family, while Prince Philip had his mind set on Gordonstoun, in the Scottish Highlands, where he himself had attended.
As has been previously reported, the Queen Mother wrote an impassioned letter to her daughter, The Queen in May 1961.
"However good Gourdonstone is, it is miles and miles away, he might as well be at school abroad," she wrote. "He would be terribly cut off and lonely up in the far north."
Despite her best efforts Prince Philip won and Prince Charles went to the rigorous Scottish boarding school. He escaped whenever he could to stay with his beloved grandmother.
The Queen Mother's love for her grandson was laid bare in yet another touching letter, this time to Charles himself.
In May 1969, just two months before his investiture, Charles, then just 20 years old, received a note from his grandmother expressing her support.
She wrote: "My darling Charles, I can't tell you what charming and heart-warming things I am always hearing about you. Everyone loves you and is proud of you and I absolutely know you will be able to do wonderful things for this country.
"Not only in leadership but by being your own kind-hearted, loving and intelligent and funny self."
It is therefore of no surprise that the Queen Mother's death in March 2002 was a devastating blow to Prince Charles.
He said in an interview: "To me, she meant everything and I had dreaded this moment."
Indeed it is clear Charles' love for his grandmother has not faded. He has given her name to the square at the centre of his model village of Poundbury, in Dorset, complete with a statue of his beloved grandmother.