WINDSOR, UNITED KINGDOM - MAY 01: Princess Sophie of Hanover, Prince Philip's sister watching him compete at the Royal Windsor Horse Show in the 1980s. (Photo by Tim Graham Photo Library via Getty Images)
WINDSOR, UNITED KINGDOM - MAY 01: Princess Sophie of Hanover, Prince Philip's sister watching him compete at the Royal Windsor Horse Show in the 1980s. (Photo by Tim Graham Photo Library via Getty Images)