Complex sentence: The programme, first broadcast on 17 March 1958, included a guest appearance by Matthews himself, at the end of the episode, and this part of the show was ad-libbed after Matthews departed from the script.
Split into simpler sentences: The programme, first broadcast on 17 March 1958, included a guest appearance by Matthews himself. He appeared only at the end of the episode, and this part of the show was ad-libbed because Matthews did not stick to the script.