Who is Barlow from The Great Train Robbery and what is their importance?

Barlow is Pierce's chauffeur. He is described as a large, tough man, who is some kind of enforcer such as the modern day mob might employ. Barlow kills Clean Willy after he goes to the police, and he later picks up the gold from the train when Agar and Pierce throw it overboard. Barlow is also responsible for helping Pierce escape from police custody during his trial.