The music Henry Bassington-ffrench plays on the phonograph and dances to in the courtyard is "Midnight, the Stars and You," made famous by its use in Stanley Kubrick's The Shining (1980) wherein it was played in the ballroom and closing scenes of that film.
Dr. Nicholson, who comes to assess another character's drug addiction, is played by series writer/director Hugh Laurie, who famously played a doctor with his own drug addiction on House (2004).