Living her life in the public eye, there's much the world has learned about the preferences and habits of Her Majesty, from her nail polish of choice - Ballet Slippers by Essie - to the way she eats pears: like a boiled egg, she cuts the top off and scoops the inside out with a spoon.
However, there's one thing she tactically hasn't shared with anyone: her favourite meal.
According to the Express, she's kept mum on this detail for a very good reason.
Former royal correspondent, Gordon Rayner, who has reported on over 20 royal tours, says the Queen knows if she shared her most cherished food, she likely wouldn't be fed anything else.
Rayner says: "As one of her staff told me: 'If she said she had a favourite meal she would never get served anything else'."
While she's kept her most treasured main dish a secret, the public does know what her favourite treat is.
According to one of her former personal chefs, she enjoyed chocolate biscuit cake so much that she'd take it with her everywhere she went.
Former Royal Chef Darren McGrady is the author of "Eating Royally". He cooked for the royal family for 15 years and shared with baking website Recipes Plus that there is a particular sweet treat the Queen is partial to: "Now the chocolate biscuit cake is the only cake that goes back again and again and again every day until it's all gone.
"She'll take a small slice every day until eventually there is only one tiny piece, but you have to send that up. She wants to finish the whole of that cake."
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McGrady said that the Queen loves the dessert so much that if a piece has been taken, she'll notice immediately.
If she has leftovers after she's been travelling, they don't go to waste - her senior chef will transport it back in a train to Windsor Castle.
Another favourite of hers is Dundee cake, a traditional Scottish fruit cake.
The Telegraph reports, "Even if she's on a flight at tea time, out will come a cuppa, a Dundee cake and some scones and clotted cream."