Complex sentence: However, the Belgian detective's titles outnumber the Marple titles more than two to one: this is largely because Christie wrote numerous Poirot novels early in her career, while "The Murder at the Vicarage" remained the sole Marple novel until the 1940s.
Split into simpler sentences: However, the Belgian detective's titles outnumber the Marple titles more than two to one. This is largely because Christie wrote numerous Poirot novels early in her career, while "The Murder at the Vicarage" remained the sole Marple novel until the 1940s.