Hmm, I'm not sure if this is strictly correct TBH. When I did the research for the MRI article I found some info in an old HMRS magazine about their 'provenance' and it wasn't to do with rebuilding standard wagons. I'll have to turn the article up and check but I thought they were rebuilds of an earlier brake van/wagon or similar, a drawing of which was in the HMRS publication. This is what provided the basic dimensions etc. I used for my drawing of the Clee Hill wagons.
Don't remember the Cromford & High Peak having any such wagons, the ascending/descending wagons were attached directly to the haulage cable. Weren't they?