Complex sentence: They had a massive box office hit with "Doctor in the House" (1954) made a star of Dirk Bogarde and led to a number of sequels, all of which would be directed by Thomas.
Split into simpler sentences: They had a massive box office hit with "Doctor in the House" (1954). The film made a star of Dirk Bogarde and led to a number of sequels, all of which would be directed by Thomas.