WOW, this is one hard machine to help you find information on and think it was probably originally made in Great Britain. There seems to be some infomation on what they call the Silver Viscount.
I would suggest when you have time to just try googling various wordings to see if you can find more information.
I've spent quite awhile trying to help you but this is going to be one long search for information with following links at various places. Maybe another member with more google savvy with wording can help you a lot better than I can. But my curiosity is really peaked when I can't find something...it just has to be out there somewhere.
Hope you find what you need as it does look like a very solid machine that could serve you well.