It is not the Rudge club (Rudge Enthusiasts Club (REC)) that sells them. If it was you would have to be a member to be able to buy parts. It is Paul Horton who sells them. Yes he is a REC member and use to be the club's spares officer.While looking on the forum, I found: it is a Miller 35E on sale by the club Rudge but at a high price. Do you know another supplier because I know there are others.
The £20 one I got fell apart during the MOT test,, Thats why I got an MT110 from hereMichel,
If cost is a problem and originality is not, and all you want is a cheap reproduction light, the Lucas MT110 is a possible alternative. They are all over eBay for around £20.
Peter B