Camilla, the Queen Consort, greets well-wishers Photo: Ben Stansall / AFP
Queen Elizabeth II "carved her own role" in a world dominated by men, Camilla, the Queen Consort, will say in a TV tribute to her.
Camilla praises her in a BBC programme to be broadcast shortly before a national minute's silence held across the UK on Sunday.
In the show, she recalls the late Queen's "wonderful blue eyes" and her "unforgettable smile".
She will also say that the late Queen "has been part of our lives forever".
Camilla was four when Elizabeth II ascended to the throne in 1952 and she tells the documentary: "I'm 75 now and I can't remember anybody except the Queen being there."
Remembering the late monarch, Camilla described "those wonderful blue eyes... when she smiles they light up her whole face".
"I will always remember that smile. That smile is unforgettable."
She also tells the BBC documentary of how her mother-in-law carved out her own role for many years from the "difficult position" of being a "solitary woman" in a male-dominated world.
"It must have been so difficult for her being a solitary woman," she says in the pre-recorded interview.
"There weren't women prime ministers or presidents. She was the only one so I think she carved her own role."
Ahead of Platinum Jubilee celebrations to mark her 70 years on the throne earlier this year, Queen Elizabeth had said it was her "sincere wish" that the then-Duchess of Cornwall would become known as Queen Consort when Charles became King.
That ended years of debate over what she would become known as.
The late Queen also called on the public to support both her daughter-in-law and son when he became the new monarch.
Camilla has joined King Charles III at a variety of public events to mark the late Queen's death and his accession to the throne.
Speaking about his wife during his first speech as monarch, King Charles said: "I know she will bring to the demands of her new role the steadfast devotion to duty on which I have come to rely so much."
The Queen Consort's tribute to her late mother-in-law will air on BBC One on Sunday during the Eve of the State Funeral broadcast from 7pm (local time).