As you can see this is
a RADIOLUX. So.. what's a Radiolux?
Well it's a cure-all magic box
known generically as a "Violet Ray" machine.
This model is quite a late example,
probably dating from the early 1930s and works from 110 volts.
Not as you may think an American supply voltage, but one dating
from pre-war days when England had an almost infinite variety
of mains voltages, both AC and DC.
Only one glass tube seems to
be present but originally there would have been a selection,
each producing a marvelous purple glow accompanied by a fizzing
noise from the discharge of several thousand volts.