A mistake on "It's Higgins, Sir" radio show

One one episode of this clever program, Higgins the butler receives a knock on the head and imagines that he is back in England and that Mr. Roberts is Sir Reginald, his former employer. However, he addresses him as "M'Lord," which he would never do to a Baronet or a Knight - those who would normally be called "Sir Whatever." A baronet is not a peer; those begin with the barons. Peers, not baronets or knights, are addressed as "My lord."