Complex sentence: In 1979 he returned to England and rejoined the Tremeloes where he remained until 1988, leaving again to focus on managing his son, Chesney, who had a hit record entitled "The One and Only".
Split into simpler sentences: In 1979 he returned to England and rejoined the Tremeloes where he remained until 1988. Hawkes left the Tremeloes to focus on managing his son, Chesney, who had a hit record entitled "The One and Only".