The Amateur Gentleman by Jeffery Farnol

THE AMATEUR GENTLEMAN is the story of Barnabas Barty, son of John Barty, former champion boxer of England and landlord of a pub in Kent. At the start of the tale Barnabas comes into possession of a vast fortune and determines to become a gentleman. His father objects, they quarrel, and settle their differences in a round of fisticuffs which Barnabas wins fair and square, whereupon Barnabas sets off for London to make his place in society -- and discover romance!