I know he was a regular on Shining Time Station, which is how Thomas the Tank Engine was originally packaged for the U.S. There was a sort of framing show that took place in a small American railway station, where a couple of kids would hang out. Mr. Conductor would appear to them - he was about a foot high - and entertain them by telling them the stories of Thomas and his friends - the setting would change from the railway station to the original Thomas adventures when Mr. Conductor blew his whistle. He also narrated the railway adventures, but I don't know whether he had narrated them in England, too. I'm not sure how many seasons he was on; he was eventually replaced by George Carlin, who was really surprisingly good and managed not to teach the children ANY of the seven words you can't say on television.