Complex sentence: It was also the second Moody Blues recording to feature him on lead vocals, the first song being their cover of "It Ain't Necessarily So", from "The Magnificent Moodies".
Split into simpler sentences: It was also the second Moody Blues recording to feature him on lead vocals. Their first song with Thomas on lead vocals was their cover of "It Ain't Necessarily So", from "The Magnificent Moodies".