The basic BR-commissioned variant stayed true to the MoT original specification, except they had linked Morton brakes, using either welded (diagram 1/108; 85% were made to this diagram), or riveted body construction (diagram 1/109; only 10% of the total number of wagons). The most common variant was an opening flap above both of the side doors. Known as a "London Traders" flap, there are conflicting ideas about its function, but it is generally thought to have been provided to make it easier for coal merchants to unload the wagon by hand.