Jimmy Jones - a movie cowboy star you may have missed

In one of the early episodes of Let George Do It, George is hired by movie star Jimmy Jones to get him through an embarrassing situation. Because of an accident, he is now terrified of horses, but he does an annual benefit for an orphanage and does not want to let them down. They notice that George and Jimmy look somewhat alike, so George volunteers to be his double - but George, being a city boy, has never ridden a horse.