This is Cadogan Hall on its south side.   This is the view most people would see as they approached the hall.  The first doorway on the left is the Artists' Entrance/Stage Door and the doorway in the middle of the arches further along is the main entrance for the audience which leads into a beautiful vestibule before entering the main auditorium.
  

This is the view from the audience in the stalls towards the stage.  The black section is the optional extension to the main stage and adds another 3+m (about 10ft in old money) in depth for the central section.

... and this is looking the other way, from the stage out to the audience.  You can see the magnificent sweep of the gallery where the seating are (comfortable) padded pews.