Complex sentence: A longer version in 1975 on the album "Metamorphosis" had been recorded on 21-23 July 1964 with Jimmy Page on guitar and Clem Cattini on drums, probably as a demo.
Split into simpler sentences: A longer version appeared in 1975 on the album "Metamorphosis". This had been recorded on 21-23 July 1964 with Jimmy Page on guitar and Clem Cattini on drums, probably as a demo.