Two four-wheel carriages mounted onto a bogie underframe supplied by the Metropolitan Carriage & Wagon Co., Ltd., of Saltley Works in Birmingham in 1922, B.21 and C.7 were allocated the fleet number F.65 and remained in service in this condition until 1971 when withdrawn in need of attention and surplus to operating requirements; the bodies were removed and scrapped in 1983 and the underframes converted to become the first bogie ballast hopper, surviving in this form until withdrawn in 2009 whereupon a further former carriage underframe (Ex.F.70) was converted into a similar hopper.  This first incarnation was scrapped in 2020.