I had one on the other S1 but want one for my daily driver that is in being repainted right now.

Pictures that show them. for rear side mount fender antenna.. really large and chrome plated... the two are slight different but I would buy either one. Pictures
will expand for a better look.

 

I know, very old thread... but I just purchased a box of XJ6 S1 parts (off a ‘70) and that exact bezel and the gasket for it were in the lot. Wondered if you discovered who made it...

 

I have one from a Mercury Wagon. Black and chtome edges. Same principle but yours are convex and the Mercury is concave.

 

No idea who made it, I finally used similar one on non electric antenna..

 

In my hunt for a new seal to mount it (which I found on xks.com), I believe I found the origin--it is a later E Type antenna base. I suspect American dealerships just slapped "whatever" onto the XJ6's that went through their hands when radios were installed... or customers asked for the "nicer one" since it isn't listed in any XJ6 parts brochures or dealership pamphlets in my possession (and I have way too many!). The seal was listed as part #38-0002... Slowly but surely I am cataloging this random parts box!