;Barry:Woodham Brothers Scrapyard, Barry, South Wales. The source of many locomotives now in preservation.
;Beames:Hewitt Pearson Montague Beames, Chief Mechanical Engineer (CME) of the London and North Western Railway 1920-1922.
;BillingtonBillinton:Lawson BillingtonBillinton, Locomotive Engineer of the London, Brighton and South Coast Railway 1912-1923
;Blue Star:An electro-magnetic form of multiple working equipment widely used by BR in first generation diesel locomotives and multiple units whereby multiple like-coded vehicles are capable of running under the control of one driver. A blue star coupling code is normally indicated on the front of the vehicle.
;B.R.