I attach some photos taken of the interior of van no. 70 prior to restoration. I have a few more pictures of the interior, and if you send me your email address via pm I will send some over. I also attach a leaflet that I found somewhere on the internet, possibly MERL, but it doesn't show anything of the interior.
I believe there are plans of the vans in the book on the book "Steam Rollers & Steam Waggons of the Worcestershire County Council" by John T Rhead; although I do not have access to my copy at the moment.