Thanks for all your posts. Benton music still trades. I've contacted Dave there who tells me the workshop was burned down over a year ago. He used to import their guitars as well.
I have already put a thread on mandolin forum..lots of hits but no replies.
Double chamber mean that the body has a second one inside the outer one and there are holes round the sides to let the sound out.The Mandolin is a flat back tear-shaped mandolin
So does anyone have a similar one they would be willing to sell to the player I met in Lancs?