Years ago, someone gave me an old electric 'oil' lamp, in bits, as there had been a failed attempt to repair it. Most of the necessary parts were there, except the cable and the actual lampholder itself. I found it again last night, probably after more than ten years.
The body was in four parts, held together by a central threaded tube, which also provides the thread for the lampholder to attach to, with the wire running up the central hole.
Today, I got a new brass unswitched lampholder and found a suitable length of lead. Having established that it had earth continuity through the whole assembly, it is now back in working order. At some point in the future, I will probably replace the plug on the rather short bit of lead with a 'torpedo' switch and then extend the lead away from there to a more practical length - when I decide where it's going. On this sort of lamp, it's often better not to have a switched lampholder, due to the access constraints, anyway.