Wow some amazingly useful info there. It's a shame I dont model GWR anymore. I dont know if some of the 1929 drawings have been updated but I'm surprised the measurements are in mm.
Thank you for sharing the info.
I have just added John Lewis's GWR Dia. BB - Stores Vans, Goods & Pilot van numbers to my blog page.
I note that on the bottom of the listing it states 'further posts' it looks greyed out but is a link to a more information.
See my first post for the Link.