The Amateur Gentleman.

A former boxing champion, now an innkeeper, is accused of stealing a watch from a party of guests at his inn, who happen to be members of English royalty. The old man is arrested and thrown in prison. His son, knowing that his father didn't steal the watch and suspecting a frame-up, follows the royal party to London, where he poses as a wealthy "gentleman" and insinuates himself into the English court in an effort to find out who framed his father and why.