Complex sentence: The song was largely written by Dave Peacock of the duo Chas & Dave, who were both fans of the club, on a request by their manager Bob England when Tottenham were having a good run in the 1980--81 FA Cup.
Split into simpler sentences: The song was largely written by Dave Peacock of the duo Chas & Dave, who were both fans of the club. Their manager Bob England requested Peacock to write the song when Tottenham were having a good run in the 1980--81 FA Cup.