Complex sentence: Peter Giles later called it one of Fripp's "cute political moves", but had become disillusioned with the lack of success of Giles, Giles and Fripp which led to his departure, leaving Lake to become bassist and singer.
Split into simpler sentences: Peter Giles later called it one of Fripp's "cute political moves". But he had become disillusioned with the band's lack of success and departed, leaving Lake to become bassist and singer.