Mary of Teck with grandchildren Princess Elizabeth, Princess Margaret and Prince Edward (Duke of Kent), LIFE Magazine, December 7, 1936

Caption reads:

Queen-Mother Mary and grandchildren: Princesses Elizabeth and Margaret Rose, Prince Edward (on lap).
Almost inevitably the dark-haired little girl at the left will some day be Queen-Empress Elizabeth. Only two things can prevent it: a child sired by her uncle, King Edward; a manchild sired by her father, the Duke of York.