Here's another ancient TV series for you! Does anyone remember the creaking door of "Inner Sanctum"? Here's the info: http://www.imdb.com/title/tt0380909/. It was 1954, when I was....9. And I can remember the startup sequence as if it were yesterday. Strange what you remember from childhood!
The opening sequence showed a progress towards a baize-covered, furniture-nail studded door, which slowly creaked open, as the announcer said something along the lines of "As we venture through the creaking door of Inner Sanctum, into the world of crime and spies and ....." And there were people sitting around a table or desk, discussing something nasty...