The character on the television show was an anaesthesiologist from Australia. It was unclear whether he was a naturalized American citizen and U.S. Army officer, or he was an Australian military officer serving with the 4077th. In the book, he was an American who had "trained in the States with McIntyre". In the film, he is an American (as he can be seen wearing the insignia of a U.S. Army Captain), but his background is not discussed.
In the TV series, Ugly John was only present in the first season. He began as a significant supporting member of the cast, often engaged in poker games with Hawkeye and Trapper, but by the end of the season he was rarely seen outside of brief O.R. scenes. (John Orchard later returned to the show for the Season 8 episode "Captains Outrageous", playing an entirely different character.)