Hi randyjawa - thanks for the offer.

I finally got some time today to have a tinker with the bike. I've taken photos and measurements (in mm) so hopefully you get an idea of what I'm looking for. It's a race for 1/8th bearings....

Side/profile:


Top:



Bottom:



Internal Diameter:



Outside Diameter:



Height:




Don't bust a gut too hard to find something, I don't want to take up too much of your time. Your help is very much appreciated though!

I tidied up the damaged race with the dremel today and fitted the headset back together. It feels OK .... and it looks like the bearings stay in place. Will do for a short-term measure and I hope one will turn up online at some point. I did the tour of my local bike shops and basically they all want to ream and face the frame of course - and all were very keen to inform me that new headsets are better than ones made in the fifties