Complex sentence: In this he submitted a picture of "Boadicea Harranguing the Iceni" which won a premium of £200 in 1843, aided by the knowledge of mural technique he had acquired by working for a panorama painter.
Split into simpler sentences: In this he submitted a picture of "Boadicea Harranguing the Iceni" which won a premium of £200 in 1843. He was aided by the knowledge of mural technique he had acquired by working for a panorama painter.