Bayonet light fixture to hardwire (Dalston E8)

Replace an old, paint-covered light with this paint-free, new-looking fixture.
You'll need an electrician, as this is hard-wired. No switch on this fixture; instead, it works on a circuit controlled by a wall or pull-switch.
Base of fixture says: Delta, (MEM), 5 M1212, Made in England.
Screws and electrician not included.
We've upgraded the light in our low-ceilinged loo to something lower-profile, so this is surplus.