Was the 'Captain' JACK in disguise? I couldn't tell!

I know this seems like it should be a simple question, but I couldn't tell if Jack Belford (Sean Pertwee's character), the friend and final champion of Clarissa, was the same person pretending to be the Captain who kept bringing bogus messages from her uncle. I couldn't decipher form the cast list if this was the case.

They looked so similar, but the behaviors certainly seem to indicate otherwise!