In about 1992, I built a dolls' house and bought these connectors from RS to use as ceiling roses. The picture shows the 'plug'. The plug came with a cover that screwed onto the threaded section. There was a corresponding 'socket' with two pins (which I use as the actual ceiling rose).
The pin spacing appears to be 3mm (definitely more than 2.54mm) and the plug diameter is about 5mm. The pin diameter is <1mm. The socket fitted over the plug. Sadly time (and children) have taken their toll, and this is the last plug. The heat shrink section hides a pea bulb. The sockets are the actual roses and are all glued into the doll's house, so if I can't find more similar plugs, I'll have to re-wire the whole thing.
The only markings I can find are 'EM' in a rectangle, and the digit '3' beside that. The pins are marked 'A' and 'B'.
Thanks in advance.