Large 300 watt bulbs (Raveningham NR14)

There are three 300 watt light bulbs with very large screw fittings. There is also a ceramic large screw holder with attached wire but no plug. Was originally bought as lights for an artists studio but guess can be used by anyone who wants a good light. They are unused but have been stored a long time and assume they still work - filaments look okay. It's very likely any replies will go into my spam account but will try and keep checking on it!!