| C.Debnath Limited | Middlesbrough | 2018 |
| C.E Company Services Ltd | Chadwell Heath | 2024 |
| C.E Pallets Ltd | Spalding | 2026 |
| C.E. Banyard Limited | Bodmin | 1982 |
| C.E. King Holdings Ltd | Burnley | 2020 |
| C.E. Moore Coachtrimmers Limited | London | 1981 |
| C.E. Projects Limited | Market Drayton | 2004 |
| C.E.A.Towne(Ship Riggers)Limited | Hull | 1951 |
| C.E.B.Rail Ltd | Lewes | 2013 |
| C.E.C. AB Ltd. | Guildford | 2007 |
| C.E.Ellison Limited | Berks | 1962 |
| C.E.Group Limited | Surbiton | 2016 |
| C.E.King Limited | Weybridge | 2012 |
| C.E.S Contracting Ltd | Chesterfield | 2020 |
| C.E.S. (Poole) Limited | Poole | 1996 |
| C.E.Turner(Engineers)Limited | Melton Mowbray | 1950 |
| C.F. Booth (Engineering) Limited | Leeds | 1980 |
| C.F. Doyle Limited | Kent | 1988 |
| C.F. Hygienic Pipes Ltd | Cumbria | 2005 |
| C.F. Whaler Limited | Spilsby | 1988 |
| C.F.B. (Boilers) Limited | Clacton | 1993 |
| C.F.Booth Limited | Leeds | 1949 |
| C.F.L. Commercials Ltd | Cheltenham | 2009 |
| C.F.Marine Ltd | Gillingham | 2022 |
| C.F.P. Hydraulic Systems Limited | Dewsbury | 1995 |
| C.F.S Brixworth Limited | Kettering | 2016 |
| C.F.Struthers Limited | Hull | 1932 |
| C.G 6 Ltd | London | 2026 |
| C.G Marine Ltd | Caernarfon | 2023 |
| C.G. & W. Young Limited | Twickenham | 1974 |
| C.G.B. Engineering Services Limited | Gorton Road Openshaw | 1992 |
| C.G.P. Engineering Ltd | Loughborough | 1986 |
| C.G.Plastics Limited | Solihull | 2003 |
| C.G.R. Polythene Company Limited | Dartford | 1990 |
| C.G.S. Machine Care Ltd | Daventry | 2003 |
| C.G.W Chestnut Fencing Supplies Ltd | Midhurst | 2021 |
| C.G.Y. (Miserve) Ltd | Exeter | 2010 |
| C.H. Barnett Ltd. | Birmingham | 1991 |
| C.H. Composites Ltd | Northampton | 2019 |
| C.H. Latham, the Baker, Limited | Manchester | 1987 |
| C.H. Power Tools Limited | Doncaster | 2000 |
| C.H.Brannam,Limited | | 1914 |
| C.H.D. Ltd | Runcorn | 2015 |
| C.H.E.F.S Ltd | Leicester | 2022 |
| C.H.Products Midlands Limited | Dudley | 1989 |
| C.H.Sausage Co.Limited | Manchester | 1967 |
| C.Harris(Wholesale Meat)Limited | Borehamwood | 1965 |
| C.Howitt Ltd | Derby | 2023 |
| C.I Fabrications Limited | Tain | 2026 |
| C.I. Stairs & Carpentry Ltd | Bristol | 2021 |
| C.I.S (Contract Packaging) Limited | London | 2009 |
| C.I.S. (London) Limited | Kent | 1998 |
| C.I.S.E. Manufacturing Limited | Knowsley Industrial Park | 2000 |
| C.I.S.M. Limited | Birmingham | 2001 |
| C.J. Covers Limited | East Yorkshire | 1990 |
| C.J. Machine Services Limited | Walsall | 1977 |
| C.J. Operations Ltd | Goole | 2016 |
| C.J. Plumbing and Heating (MCR) Ltd | Manchester | 2020 |
| C.J. Sinclair Limited | Ramsgate | 1963 |
| C.J.C. Joinery Ltd. | Wivelsfield Green Haywards Heath | 2002 |
| C.J.C.(Electrical)Limited | Tadworth | 1964 |
| C.J.E. Micro's Limited | Littlehampton | 1987 |
| C.J.Lewis(Ashby)Limited | Ashby De La Zouch | 1945 |
| C.J.Mcmillan Ltd | Crediton | 2018 |
| C.J.N. Engineering Limited | Newport | 2001 |
| C.J.S Crankshaft & Machine Ltd | Wigan | 2024 |
| C.J.S Heritage Engineering (Wigan) Ltd | Wigan | 2024 |
| C.J.S Manufacturing Ltd | Bolton | 2021 |
| C.J.S. Technology Ltd | Leicestershire | 2003 |
| C.J.W. Printers Limited | Huddersfield | 1982 |
| C.Joyce Mech Ltd | Danderhall | 2021 |
| C.K Powder Coatings Limited | Walsall | 2013 |
| C.K. Beckett Transformers & Switchgear Limited | Barnsley | 2012 |
| C.K. Crane (International) Limited | Burton-On-Trent | 2018 |
| C.K. Foods (Processing) Limited | Hull | 2005 |
| C.K.L Holdings Limited | Howe Bridge | 2002 |
| C.K.S. Precision Ltd. | Lutterworth | 1986 |
| C.L. Brookes Limited | Chesterfield | 1962 |
| C.L. Electrical Controls Limited | Bristol | 2004 |
| C.L. Fabrications Limited | Aylesford | 2004 |
| C.L.A Fabrications Ltd | Wednesbury | 2013 |
| C.L.A. Tools Limited | Coventry | 1974 |
| C.L.H Railway Services Ltd | Crewe | 2024 |
| C.L.L.Fabrication Ltd | Hartlepool | 2026 |
| C.L.M. Services Limited | Wallasey | 1996 |
| C.L.Tyres Limited | Herts | 2019 |
| C.L.U.B. Hair Ltd | London | 2020 |
| C.M Extract Ltd | Middlesbrough | 2025 |
| C.M. Optical Ltd. | Bathgate | 2008 |
| C.M. Supplies Limited | Nottingham | 1994 |
| C.M.C Carpentry Ltd | Southend-On-Sea | 2022 |
| C.M.C. Machinery UK Ltd | Milton Keynes | 2021 |
| C.M.F. Limited | Maidenhead | 1982 |
| C.M.I. Lexaire Ltd | Nelson | 2005 |
| C.M.I. Limited | Newark | 1980 |
| C.M.R. Jewellery Limited | | 1976 |
| C.M.Y.Joinery Limited | London | 2024 |
| C.Macphail Ltd | Stornoway | 2019 |
| C.Mckenzie Ltd | Buckie | 2025 |
| C.Me Smart Designs Limited | Kettering | 2017 |