Catapilla was an English group built around guitarist Graham Wilson, saxophonist Robert Calvert and singer Anna Meek. For Changes, their second album, the band was rebuilt around them with Brian Hanson on drums, Carl Wassard on bass and Ralph Rolinson on organ and electric piano. Produced by Colin Caldwell, it came out on Vertigo in June 1972, and the group broke up shortly after.

There are only four tracks, two of them past the twelve-minute mark. Calvert's saxophones, often electrically treated, carry the long improvised sections, while Meek, who wrote all the lyrics, sings over them. The music sits between the heavier progressive rock of the early Vertigo roster and British jazz-rock, with hypnotic, repeated bass and organ figures under the soloists.

Japanese CD reissue by Belle Antique in a gatefold die-cut mini LP replica with obi and Japanese liner notes, SHM-CD, remastered.