England, 21st April, 1939, King George VI out riding his horse with his daughters Princess Elizabeth, later Queen Elizabeth II, and Princess Margaret (left) in Windsor Great Park [Getty Images]

England, 21st April, 1939, King George VI out riding his horse with his daughters Princess Elizabeth, later Queen Elizabeth II, and Princess Margaret (left) in Windsor Great Park (Photo by Popperfoto via Getty Images/Getty Images)

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