Complex sentence: The distinctive theme tune is an arrangement of Camille Saint-Saëns' "Danse Macabre" by Julian Stewart Lindsay, who also wrote the underscore for the first three series, after which the underscore for the remaining series and two specials was written by Rick Wentworth.
Split into simpler sentences: The distinctive theme tune is an arrangement by Julian Stewart Lindsay of Camille Saint-Saëns's "Danse Macabre". Lindsay wrote the underscore for the first three series, after which the underscore for the remaining series and two specials was written by Rick Wentworth.