| B.A.S Limited | Cwmbran | 1982 |
| B.A.T (U.K. and Export) Limited | London | 1929 |
| B.A.T. China Limited | London | 1914 |
| B.A.W Commercials Limited | Dartford | 2012 |
| B.Allsop Limited | Holmfirth | 1964 |
| B.B ENG Limited | Littlehampton | 2006 |
| B.B. Clarke (UK) Ltd | Watford | 2000 |
| B.B. Grout (Essex) Ltd | Canvey Island | 2023 |
| B.B. Grout Limited | Essex | 1966 |
| B.B. Mathias & Co. Limited | Haverfordwest | 1976 |
| B.B. Moulding Limited | Bishop Aukland | 1993 |
| B.B. Price Limited | Cradley Heath | 1930 |
| B.B.C.S. Limited | Swadlincote | 2003 |
| B.B.F.Co.,Limited | Stoke On Trent | 1930 |
| B.B.R. Graphic Engineers (Yorkshire) Limited | Ossett | 1983 |
| B.C Airflow Ltd | London | 2017 |
| B.C. Electrical Techniques Limited | Aylesbury | 1950 |
| B.C. Metal Finishing Services Limited | Bolton | 1987 |
| B.C. Tube Benders Limited | Suffolk | 1979 |
| B.C.B. International Limited | Derby | 1979 |
| B.C.C. (NE) Limited | Durham | 2004 |
| B.C.I. (Stretchers) Limited | East Boldon | 2000 |
| B.C.T.Engineering Limited | Surrey | 1971 |
| B.C.V. Coachworks Ltd | Bryncoch | 2016 |
| B.C.V. Limited | Chavey Down | 1987 |
| B.Cadman Limited | Notts | 1964 |
| B.Conway (Tail Lifts) Limited | Oldham | 1984 |
| B.D Wind Solution Limited | Newcastle Upon Tyne | 2025 |
| B.D. Direct Limited | Warley | 1936 |
| B.D.F. Commercial Ltd | Eastbourne | 2012 |
| B.D.G. Manufacturing Ltd | Birmingham | 1941 |
| B.D.R. Micro Instruments Limited | Chelmsford | 1991 |
| B.Dester Services Ltd | Aberdeen | 2018 |
| B.Duffy Mechanical Ltd | Middlesbrough | 2014 |
| B.E. Chaplin (Gunmakers) Limited | Winchester | 2021 |
| B.E. Cook Limited | New Barnet | 1974 |
| B.E. Electricals Services Limited | London | 2025 |
| B.E. Loveday Precision Engineering Limited | Tiverton | 1978 |
| B.E. Stannard Engineers Limited | Dagenham | 1960 |
| B.E. Wedge Holdings Limited | West Midlands | 1938 |
| B.E.C Global Limited | Hamshire | 2003 |
| B.E.E.E.D PVC Systems Ltd | Omagh | 2017 |
| B.E.L. Precision Engineers Limited | Accrington | 1987 |
| B.E.M Projects and Facilities Management Limited | Birmingham | 2016 |
| B.E.N Locksmiths Ltd | Basingstoke | 2013 |
| B.E.S. Controls Limited | Brierley Hill | 1984 |
| B.E.S.T. Designs Limited | London | 1996 |
| B.E.S.T. Electrical & Engineering Ltd | Long Eaton | 2000 |
| B.F Electrical Ltd | Gloucester | 2019 |
| B.F. Engineering Links Ltd | Spalding | 2025 |
| B.F.S. Enterprise (Fabrications) Limited | Beccles | 1978 |
| B.F.S. Sheet Metal & Engineering Limited | Send | 2003 |
| B.F.T. (Engineering) Limited | Worcs | 1966 |
| B.Fulgoni & Sons Limited | Porthcawl | 1962 |
| B.G. Developments Limited | Brierley Hill | 1983 |
| B.G. Pavers Limited | Preston | 1990 |
| B.G. Penny & Company Limited | Ibstock Road, Coventry | 1985 |
| B.G. Sports International Ltd | Colne | 1995 |
| B.G.Bullas Limited | West Midlands | 1963 |
| B.G.M.Plastics Limited | Shepley | 1971 |
| B.G.S Motors & Mowers Ltd. | Bridgend | 1994 |
| B.G.Sheet Metal Co.Limited | Birmingham | 1963 |
| B.G.T. Automatics Limited | Farnborough | 1965 |
| B.Gutsy Ltd | Market Drayton | 2023 |
| B.H. Refrigeration Limited | Whitby | 2005 |
| B.H. Repairs Limited | Mansfield | 2003 |
| B.H. Seals (Bham) Limited | Birmingham | 1994 |
| B.H. Transmission Services Limited | Wednesbury | 1992 |
| B.H. White & SON Limited | Bridgwater | 2008 |
| B.H.B. (Goole) Limited | Goole | 1995 |
| B.H.Brawn & Co.Limited | Wellingborough | 1957 |
| B.H.C. Limited | Enniskillen | 1995 |
| B.H.Leake & Sons Limited | Birmingham | 1972 |
| B.H.M. Knitwear Limited | Leicester | 1972 |
| B.H.O.S.S Microsystems Limited | Crawley | 1990 |
| B.H.W. Ceramics Limited | Telford | 1973 |
| B.Hague & Company Limited | Nottingham | 1918 |
| B.I.G. (Brackets and Bolts) Limited | Colchester | 2000 |
| B.I.G. Engineering Limited | Middlewich | 1977 |
| B.I.L. Steels Limited | Kidderminster | 1993 |
| B.J. Associates Limited | Hampshire | 1990 |
| B.J. Control Panels Limited | Nottingham | 1982 |
| B.J. Engineering (Services) Limited | Willenhall | 1979 |
| B.J. Press Limited | Truro | 1987 |
| B.J. Stainless Fabrications Limited | Manchester | 2002 |
| B.J.Corrigan Limited | Preston | 2011 |
| B.J.M.(Upholstery)Limited | Portsmouth | 1966 |
| B.J.Plastics(Wolverhampton)Limited | Matlock | 1971 |
| B.J.R. Systems Limited | Hertfordshire | 1997 |
| B.K. Pulse Limited | Newport Pagnell | 1995 |
| B.K. Sealants Limited | St. Helens | 2025 |
| B.K.T.(Rings)Limited | | 1950 |
| B.L. Controls Limited | Manchester | 1998 |
| B.L.C. (Scotland) Limited | Glasgow | 1998 |
| B.L.D. Brick Services Limited | Cranleigh | 1993 |
| B.L.S. Foods Limited | Wigan | 2009 |
| B.L.T. Circuit Services Limited | Luton | 1988 |
| B.Lewis Associates Ltd | Hinckley | 2008 |
| B.Lucille Ltd | Twickenham | 2024 |
| B.M. Graham Limited | Farnham | 1976 |