Retro Black "Bakelite" effect, Edison Screw, Bulb Holder, available in two styles - Plain or threaded skirt.
E27 Edison Screw
Threaded - 10mm threaded entry and comes with shade rings.
Both come complete with black twist lock cord grip.
Dimensions: Diameter - 40mm, Height - 85mm (with cord grip)
Always use a qualified electrician for any electrical work.