Thanks Rob! No rush on the pics.
I got thinking about this thingy and its configuration with the reel mount on top and had some luck finding a photo of it in use! The photo I found was of a 2RCHA L5 with E Battery (Para) taken in the 80's. The configuration is identical!
I thought the L5 might be a candidate as the trails couldn't hold the Tannoy or reel holder.
The pic is from
http://home.cogeco.ca/~jukeboxpete/I...es/Page427.htm