Complex sentence: After working for a time in theatre, Nimmo spent several years with the BBC, partly on adapting other writers' stories for television, including 40 episodes (eight "stories") for "Jackanory" readings.
Split into simpler sentences: After working for a time in theatre, Nimmo worked for several years with the BBC. Part of that time was spent adapting other writers' stories for television including 40 episodes (eight "stories") for "Jackanory" readings.