Queen Elizabeth's Young Granddaughter Breaks Arm Royal officials say one of Queen Elizabeth II's granddaughters has broken her left arm after falling off her pony. Buckingham Palace says 8-year-old Lady Louise Windsor is now resting at home after being treated by doctors following the accident at Windsor on Wednesday morning. Lady Louise is the daughter of Prince Edward and his wife Sophie, Countess of Wessex. The palace said that Lady Louise was treated by doctors and that her mother had canceled plans to go to Manchester with Edward in order to stay with her daughter. Lady Louise was a bridesmaid in the wedding last year of her first cousin, Prince William, and the former Kate Middleton.