https://screenrant.com/doctor-who-ian-barbara-reference-chris-waites-sign-1960s/

Doctor Who (https://screenrant.com/tag/doctor-who/)'s The Devil Chord (https://whatculture.com/tv/doctor-who-the-devils-chord-review-8-ups-2-downs?rf=homepage) made a reference to a 1963 character that those fans familiar with the classic series would have recognized.