Harry H Corbetts biography is a good read. When approached for Steptoe he was playing lead in a Shakespear play, when he appeared in several plays on TV, word was spreading about his talent and other actors would go out of their way to see him Perform. He was described at the time as potentially being England's own Marlon Brandon.
He was a legend as Steptoe, I get the impression he wanted a return to serious acting but...… and of course he died tragically young.
He added the H to his name to avoid being confused with Sooty's friend, Harry Corbett.