I Know Him So Well was a song written by Benny Andersson and Björn Ulvaeus from pop group Abba and Tim Rice for the concept album and musical Chess. The original song was sung as a duet by Elaine Paige and Barbara Dickson.
The musical revolves around a chess tournament between an American and Soviet grandmaster and the struggles of being in love. Chess was a theatre production that was politically charged for its time because of metaphorical references to the 1980s Cold War as a manipulative game.
The duet was released as a single which reached number one in the UK Singles Chart for four weeks in 1985. This recording remains in the Guinness Book of Records as the biggest selling UK Chart single ever by a female duo.
Later versions of I Know Him So Well was covered by Whitney Houston and her mother Cissy Houston, Geraldine McQueen and Susan Boyle for Comic Relief 2011, Melanic C and Emma Bunton from the Spice Girls and many more.