Royal Spectators At The European Horse Trials -- Two keep your spectators, perched on the roof of the Royal land rover for the best view, during the speed and Endurance That of the European Horse Trials at Windsor are 4-years-old Princess Anne and her "big" brother Prince Charles (6), equipped with binoculars.The Royal Family have been ***** daily spectators during the four days (May 1th. to 21st) of the European Horse Trials at Windsor Great Park, in which horse seen and horsewomen of ten nations have been competing. February 28, 1955. (Photo by Fox Photos).