Complex sentence: In 1993 he was cast as Cuthbert Lilly in Zzzap!, the character proved so successful, that he got his own Spin-off show entitled Cuthbert's Diary (which was narrated by Waites).
Split into simpler sentences: In 1993 he was cast as Cuthbert Lilly in Zzzap! The character proved so successful that he got his own Spin-off show entitled Cuthbert's Diary (which was narrated by Waites).