Is there one stage door for all the theatres at the National Theatre or is there a door for each theatre and if so, are they accessible to the public or do you have to buy a ticket and see a show to get to the door?
There's only one stage door and you don't need to have ticket to access it. However, the NT has endless doors and, since I assume we're talking about Angels in America, the cast might want to use other doors to avoid the crowd after a 3.5 hours show.