I bought this 1939-dated Ever Ready ARP lamp on eBay recently. It was in a pretty poor state with a lot of surface corrosion. However, a little elbow grease, paint stripper, rust remover and some black spray gloss brought it back to life.
The type of battery required for lamps such as this - the No. 800 or similar - are no longer made but bright sparks have 3D-printed various battery replacement holders. As an added touch, the vendor I used also printed out a facsimile of the Ever Ready label from the 1930s.
The battery holder takes two C2 batteries. I replaced the bulb (in the first image the original bulb is on the right) and the lamp works fine. The light, I have to say, is very weak. The glass is intentionally frosty to further reduce the amount of light emitted. However, in the blackout I imagine it would suffice.
Battery adapters are available from this seller on eBay.
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