MGA, MGB, MGB GT Midget Number Plate & Map Light, MG part; BHA4283, Lucas Type L534.
As will as number plate lights this light is also used in a number of classic cars as a map light.
Takes a ba15s Bulb, Lucas LLB207 available in my ebay shop.
As fitted to numerous British classic cars like; Hillman Imp, Austin Cambridge A40, Austin A50, A90, Aston Martin, Bentley, Jaguar, Healey, MG, Rover, Riley, Sunbeam, Triumph, Morris, Wolseley, Lotus Elan & Lotus Seven & Caterham, Oxford, Cowley etc.
See my eBay shop for other Mini, MG & Triumph items and and chrome plinths to go with these lights.