British Railways built a single batch of 150 wagons for anhydrite from Long Meg Quarry on the Settle and Carlisle. They well known to enthusiasts and were vacuum brake. Less well known is that some 'escaped' to work from Wellingborough in the mid 1970s. The N gauge society makes a kit available for these. Scale drawings in: Monk-Steel, David (2022) An illustrated history of British Railways Hopper Wagons. HMRS publishing, Butterley Station, Derbys. 248 + iv pages ISBN 978 0 902835 42 9
NOTE – These photographs are low quality scans and may not print well.