I got another look today and as Rik said it seems to be a WD 16H. The frame number is W 36833 ( it's feint ). WD hints : field stand lugs by LH rear footrest, friction adjuster nut. I took some photos with my phone, and they're a##e. The sidecar looks Norton, loops over the wheel. The body mounts on four half leaf springs. Is there any way of telling if the bike came with a chair originaly ?
The toolbox and battery carrier are post-war too, and the footrest hangers are the long civilian type. Somehow it seems more like a postwar bike that needed frame and forks after accident damage rather than a re-engined WD bike, but that's just a guess. The front mudguard is not Norton.
I'm not well-up on the sidecars but it does look like a Norton chassis. I can't really see the body. Ron will probably know better.
My feeling is that this would be a better project for someone looking to make a nice civilian style sidecar outfit of indeterminate date rather than as a basis for a WD project, unless you particularly want the sidecar and can perhaps haggle a bit on price.
Thanks Kostas, I should have taken the camera. The wheels look rebuilt and the exhaust, headlamp, etc look recent, but no doc,s. I think it might be dificult to get age related in the UK without restamping the frame as a postwar big 4. The dealer is going to clean it up and put some Norton transfers on it. He says there is a dating certificate and it's advertised as a 1938 16H. I said most of it was post war, he's looking into it. As I said earlier he wants about £3000 for it, probably more after cleaning etc. You can find it under Venture Classics , in Somerset.