OR lamps are one of the few applications where 3-Way lamps were also widely used in Europe. Usually one of the filaments was rated 12V or 24V, intended for battery operation in case of a mains power failure.
hello
I have one of these bulbs made by Narva, however the base is slightly different to the normal three mogul base E39d). Apart from being 40mm long the center contact is not flush bot extruded. Im not sure of that sockets designation however maybe EF40-d?
Best regards,
Alex