It is a Bulgin L1436 connector. The part in your picture is a L1436/s The part that goes on the mains cable is a L1436p. I think these are now obselete but you might find some on Ebay.
Yes Bulgin type connector, and as Les says, now obsolete. If you join Vintage Radio Forum (free) and post a request you could be lucky. Some member have a multitude of different and unusual fasteners/connectors. John
These connectors don’t meet the latest safety standards. However unlike the similar round bodied Bulgin mains connectors with threaded covers it is not inherently dangerous. It has a cable clamp and the cover needs a tool to remove. Perfectly good to use as a replacement for existing equipment. Technically not legal to use on something newly built