The London Underground B Stock was built in 1905 for the Metropolitan District Railway (now the London Underground's District line). 420 vehicles were built, formed into sixty 7-car units. 140 cars were built, divided equally between the two suppliers, in Britain by both Brush Traction and Metropolitan Cammell, with the remaining 280 built in France by Ateliers. 192 of the cars were driving motors, thirty-two were control trailers and the remaining 196 cars were trailers. These units were wooden-bodied and were based on the prototype A Stock.