They added (or fixed) a fire exit sign at the end of the hall, which is now lighted up in the evening.

As it is in a small alcolve beyond the 30 or so yards to where the photocopier at the end of the hall used to be, it doesn't really affect the pictures much (apart from the reflections).

Here is a new set of reference pictures, at 4s, 2s and 1s, with the same settings, to get an idea of how it affects the subsequent beamshots.