Complex sentence: During the late 1970s and the 1980s, Miss Terri Foley trained and conducted the choir, who gave the Music for Pleasure record label its only UK No.1 single.
Split into simpler sentences: During the late 1970s and the 1980s, the choir were trained and conducted by Miss Terri Foley. It was the Music for Pleasure record label's only UK No.1 single.