Hi The Royal Academy of Arts has an exhibition on George Bellows, a famous American painter from the early 20th century. A large portion of the paintings and sketches are of classic boxing matches and club fights. There are some great picture of Jack Dempsey and Jack Johnson as well as some amazing club fighting paintings. It's only £10 and is worth a visit for any boxing history fan I was there for about an hour so its good value. I just need to save up a few million pounds to buy one of the paintings now.
I saw the poster for this from a passing train whilst in London the other week, would actually consider going