It's long been a topic of curiosity among royal watchers – just how much sway the Queen has in the lives of her younger family.
Now the Duchess of Cambridge has revealed her grandmother-in-law doesn't so much pull the strings, but she does act as a mentor.
For Prince George though, the Queen is just the great-grandma he calls "Gan Gan".
In the 63 years since her coronation, it's been extremely rare for Queen Elizabeth II to share any candid moments – until now.
Just a few months short of her 90th birthday, a documentary crew will take a behind-the-scenes look at her life as Queen, and as Grandma.
"George is only two-and-a-half. He calls her Gan Gan. She always leaves a little gift or something in their room when we go and stay and that just shows I think her love for her family," says Kate Middleton.
The Duchess talks affectionately about the Queen, but cast your mind back five years to just her second public engagement in London, signing the condolence book for the Christchurch earthquake at New Zealand House.
The nerves were clear and she says the Queen has helped her with that.
"The most memorable engagement for me I suppose was an away day to Leicester, and I went without William so I was rather apprehensive about that," says Kate.
"She was very supportive. She took the time to make sure that I was happy and looked after for that particular occasion, which probably in everything she was doing is a very small element. It shows just how caring she is really."
At times, the Queen has been accused of meddling in her family's affairs, but not according to Kate.
"She's been very generous and not forceful at all in any of her views. I feel she's been there as a gentle guidance for me."
Prince William also appears in the documentary insisting the Queen has supported him to "carve his own part".