Mark Anthony Peter Phillips is an English Olympic gold medal-winning horseman for Great Britain and the first husband of Anne, Princess Royal, with whom he has two children. He remains a leading figure in British equestrian circles, a noted eventing course designer, and a columnist for Horse & Hound magazine.

Personal Aide-de-Camp to the King is an appointment in the Royal Household of the United Kingdom. It is distinct from that of other aides-de-camp, in that it is only bestowed on members of the British royal family holding military rank. The appointment may be signified by the post-nominal letters 'ADC(P)'. It is an honorary role with few duties or responsibilities attached; in the 20th century the Personal Aides-de-Camp were specifically listed as riding close behind the Gold State Coach at each Coronation, and walking or riding close behind the Gun Carriage at each State Funeral, of a monarch.