Complex sentence: While Taylor was the guitarist (later switching to bass) and Rhodes played the synthesizer, Duffy was the band's vocalist/lyricist and bassist, when bass player Simon Colley joined, Duffy moved to drums.
Split into simpler sentences: While Taylor was the guitarist (later switching to bass) and Rhodes played the synthesizer, Duffy was the band's vocalist/lyricist and bassist. When bass player Simon Colley joined, Duffy moved to drums.