LNER designed BK container to Diagram 31. 200 containers were built to this design.

In LNER days, these containers were painted Oxford Blue with yellow lettering in a "Zig-Zag" colour scheme promoting furniture removal.

These would be seen on conflats, Lowfits*, 3 plank wagons and high sided open wagons. High sided wagons were sometimes used to prevent the doors being opened in transit and pilfering of the load.

*BR prohibited use of Lowfits for containers but photos show them being used in LNER days