Tony, I've heard docents in various places say that a corner chair was designed to double as a potty; or designed so a "gentleman" could be seated comfortably with a sword hanging from his side!
I saw that same Antiques Roadshow with the corner chair. They identified it as a New York chair. It looked exactly like one I made copied from one of Sack's good, better or best books. Sack says it's a New York chair with the original being in the Karolik collection in Boston's Museum of Fine Arts. The main difference in mine and the one on TV is that on mine (and the original) there is some modeling on the inside of the splat; whereas the one on TV seemed to be completely flat on the inside of the splat. I cant speak for the original but I do guarantee that mine has never been used as a potty!