Neville St. Clair's final quotation, as he is burning the beggar's clothes is a misquotation from Hamlet, Act 5, Scene 2, when Horatio says "Good night, sweet prince, and flights of angels sing thee to thy rest."
Guest star Clive Francis who plays Neville St. Clair, once wrote a stage adaptation of the Sherlock Holmes novel The Hound of the Baskervilles, which has been produced and staged in repertory theatre (eg Oldham Coliseum, 2012).