That look just like the plug that connects the mains power supply to a Nikon film scanner and also what used to be a standard hot water kettle in UK but that is for the normal 240V. Is that the power supply 'in' or the low voltage 'out' socket, I cannot read the writing.
As you are in UK, you could try a company in UK called RK Photographic that has some spares for Kaiser enlargers. I think they are one of the few still in production so you could also try Firstcall Photographic near Taunton in Somerset or Second Hand Darkroom supplies which is in I think Oxfordshire.