In 1969 BR built 52 covered hopper wagons to carry limestone to steelworks. The design was based on the Merry go round coal carrying hoppers of the time. A further 5 were built in 1977 as a replacement for some damaged wagons.
A scale drawing of a CBA is in Monk-Steel, David (2011) Merry-go-round on the rails. HMRS publishing, Butterley Station, Derbys. 196 pages ISBN 978-0-902835-30-6. and also Monk-Steel, David (2026) An illustrated history of British Railways Covered Hopper Wagons Part 1 Gravity discharge hoppers. HMRS ISBN 978 0 902835 45-0
