A Durex Advertising Clock c1930
The Greenwich time reference is of course to London-Greenwich mean time.
There are makers labels and details on the back.
It can either hand on a wall or stand up as shown in the pictures.
I have never seen or owned one of these in 25 years.
Condition: Good but with some staining to the white perspex from age...not seen when the lamp is lit.
Specifications: Height: 15.5 inches, Width: 12 inches, Depth: 7 inches