Built in 1987/88, this was a conversion of BPA wagons involving removal of the body and replacement with high ends and bolsters. They were used to carry steel plate or billets from Scunthorpe, or aluminium ingots from Fort William. About 50 wagons were rebuilt - coded BMA-A, but changed in 1999 to BNA to distinguish them from the BMA wagons rebuilt in 1989 from BDAs.

Note: the production wagons converted from BPAs differed from the prototype wagon 965077. This was a very unusual wagon indeed, as the conversion involved welding most of two SPA wagons (minus the axleguards etc., but including the solebars) to the solebars of the BPA. The wagon ran for several years with the SPA sides and ends in place. The doors were later removed and BMA bolsters fitted which matched the other wagons, but the floor was higher because of the double solebars. The height of the ends was also raised in a similar way to OTAs.