Thanks for the suggestions. I've just had a stroke of luck talking to someone who works in the theatre/concert lighting industry. He says "ML" stands for "Martin Lunel", and I can now track down pictures of similar sockets doing a Google search. It appears it isn't a German eagle symbol, although I had wondered that myself. Apparently they were still available 10 years ago (when he last bought one). DJK, can you remember which metal-bodied sockets were unsafe? Naturally I must use a design which is safe. I've disassembled a socket and can't see anything which could cause the body to become live. It looks pretty safe to me.
Thanks for the help.
Chris
