Robin wrote:

It was a standard physics laboratory supplies lamp, used to make
an image of the filament in things like pin-hole viewers/cameras.

It might not be mains voltage. If it's an uncoiled filament, it
isn't long enough. If it's a single coiled filament, it might be.

I thought hairpin style filaments weren't coiled - hence the tubular
design (up to at least 8 inches long IIRC) to make them long enough.

It is indeed coiled.

Daniele