LNW socket lamp irons. I'm not sure why this railway company decided to be different from everyone else in the way they attached their lamps to locomotives, but as a modeller I wish that everyone else had done the same thing.
The sockets are supplied as very neat lost wax castings. All I had to do was snip them off from the fret and clean the backs with a file. Then, after tinning with conventional solder, I used the RSU to fit them to the loco. That's a nice quick process and a whole lot less painful than bending bits of etch to make a conventional lamp iron. The results are a whole lot less vulnerable to handling too !