Here's one I'll add to the list and let one of you Brits rate. Johnny Douglas, who beat Reg Baker for the 1908 Olympic Middleweight gold medal. He got tagged with the Nickname "JWHT" (Johnny Won't Hit Today) while captain of the British Cricket Team. He was also a footballer.
An article about him is at the following address:
http://www.boxing-monthly.co.uk/content/0402/two.htm