Conditions presumably varied from excellent to horrible, depending on
the company, but one fairly constant thing is that conditions for
workers tended to be on the functional side, with little attempt to
domesticate things.  Showrooms were, of course, made really fancy, and
clearly companies thought that buyers might find factory conditions
a little primitive -- I've seen one photo where it's obvious that the
curtains on the windows are hand-drawn!

In 1910 a series of photos were taken of the London (Hayes) Aeolian
piano-roll factory, which was pretty new at the time.  These can be
found in various places, but a convenient location is on a local
history site.  This contains all the 1910 pictures plus Rex Lawson's
photos of the factory in the 1970s:

  http://middx.net/photopost/showgallery.php/cat/842 

The working conditions look pretty good: electric light, real curtains
at some of the windows, all spacious, clean and tidy, and you can see
heating pipes running round the walls.

I'd imagine that this kind of working environment was typical of
better-run companies in those days.  I have a catalogue with a large
set of photographs of the Lexow piano-action factory in Berlin that
shows a pretty similar setup.

Julian Dyer