Keith Peacock was born in Barnehurst, Kent, England, on the 2nd May, 1945. Keith played his entire professional career for Charlton Athletic, making over 500 Football League appearances between 1962 and 1979. On August 21st, 1965, while playing for Charlton, he became the first substitute ever to be used in the Football League when he replaced injured goalkeeper Mike Rose after 11 minutes of an away match against Bolton Wanderers.
In 1979, he became Player/Assistant Coach with the Columbus Magic in the ASL, then his old friend Gordon Jago asked him to become his assistant, in a role which would last until 1982. Keith also made 2 appearances during the 1980-81 indoor season.
Keith was manager of Gillingham between 1981 and 1987 and then Maidstone United between 1989 and 1991. He later served as assistant manager at Charlton Athletic before stepping down after the resignation of Alan Curbishley in 2006. He moved to West Ham United where he became first a scout and then assistant manager under Alan Pardew and Alan Curbishley. He ended this role at the end of the 2006–07 season.
Keith, married to Lesley and has a son, Gavin (born 1967), who also became a professional footballer, and a daughter, Lauren.