During his 23-year run as full-time commentator, Walker became known for his animated enthusiasm, authoritative voice and comical blunders – dubbed "Murrayisms" by fans – during live races. His commentary voice has been likened to a "screech and resembles a 500cc engine being revved up". He retired from full-time commentary after the 2001 United States Grand Prix, but returned to broadcasting part-time in 2005 and made occasional appearances on the BBC, Channel 4 and Sky Sports F1.