| C. Atkinson Limited | Liverpool | 1986 |
| C. B. CNC. UK Limited | Half Way, Sheffield | 2007 |
| C. B. Electrical Engineers Limited | Bolton | 2000 |
| C. Batten Carpentry & Joinery Ltd | Belvedere | 2024 |
| C. Blumsom Limited | Essex | 1955 |
| C. Brown & Sons (Steel) Limited | Birmingham | 1954 |
| C. C. Hydrosonics Limited | Hertfordshire | 1973 |
| C. C. Jensen Limited | Spennymoor | 1990 |
| C. C. K. Stainless Products Limited | Sowerby Bridge | 1986 |
| C. C. Marine Services Limited | Chichester | 1981 |
| C. C. Windows Ltd | Edinburgh | 2022 |
| C. Caswell Engineering Services Limited | Rossendale | 1974 |
| C. Cryer Ltd | Chippenham | 2008 |
| C. ET W. Holdings Limited | London | 1990 |
| C. Fincken & Co. Limited | Nr. Bromyard | 1986 |
| C. G. Orme Electrical Ltd | Swadlincote | 2012 |
| C. Gunn Electrical Services Ltd | Thurso | 2024 |
| C. Handley Ltd | Mansfield | 2005 |
| C. J. Hortons Limited | Bepton | 2008 |
| C. Lawrence Upholstery Ltd | High Wycombe | 2008 |
| C. LM Marine Services Limited | Llandudno | 2011 |
| C. M. Collective Limited | Bath | 2013 |
| C. Morgan Pallets Limited | Merthyr Tydfil | 2002 |
| C. Norris (Spring Specialists) Limited | Milnrow Rochdale | 1962 |
| C. O. B. Luton Limited | Birmingham | 1975 |
| C. P. Carpets (Kidderminster) Limited | Clifton Down Clifton | 1976 |
| C. P. Sheds Ltd | Exeter | 2015 |
| C. R. D. Bespoke Gates Limited | Evesham | 2018 |
| C. Rice Engineering Limited | Stockport | 2012 |
| C. Roberson & Co. Limited | | 1985 |
| C. Scope International Limited | Ashford | 1958 |
| C. Toms and SON Limited | Fowey | 1941 |
| C. U. Lighting Limited | Ware | 1987 |
| C. W. Bream Limited | Nuneaton | 2003 |
| C. Warrick & SON (Concrete) Limited | Spalding | 1946 |
| C. Y. Finishes Limited | Winchester | 1983 |
| C.& P.Development Co.(London)Limited | Hailsham | 1951 |
| C.& S.Steels(Wolverhampton)Limited | Bilston | 1964 |
| C.A. Bengry Limited | Near Longton, | 1939 |
| C.A. Honemaster Limited | Cheltenham | 1984 |
| C.A. Sharp Ltd | Shoreham-By-Sea | 2025 |
| C.A. Treble (London) Limited | London | 1999 |
| C.A.B. Heating & Plumbing Limited | Cardiff | 2009 |
| C.A.B. Special Batteries Ltd. | Plymouth | 1982 |
| C.A.Carpentry Ltd | Uxbridge | 2019 |
| C.A.E.S. Holdings Limited | Carlisle | 2016 |
| C.A.E.S. Limited | Carlisle | 1972 |
| C.A.J Renewable Solutions Ltd | Hartlepool | 2013 |
| C.A.L.I.S. (U.K) Limited | Tredegar | 2001 |
| C.A.M Automation Ltd | Washington | 2013 |
| C.A.P. Carpentry and Joinery Ltd | Ingatestone | 2017 |
| C.A.R Tooling Ltd | Coventry | 2012 |
| C.A.S. Engineering (NI) Limited | Belfast | 2006 |
| C.A.V. Profilers (Sheffield) Limited | Meadowbank Road Rotherham | 2000 |
| C.A.W. (Cornwall) Limited | Truro | 1987 |
| C.Aiano and Sons,Limited | London | 1946 |
| C.And W.Electronics Limited | Wolverhampton | 1969 |
| C.B Technology Ltd. | Livingston | 2002 |
| C.B. Kaymich & Co. Limited | Sheffield | 1977 |
| C.B. Payne (Plastics) Limited | Stroud | 1973 |
| C.B. Refrigeration Limited | Hengoed | 1985 |
| C.B. Scotland Ltd | Livingston | 2021 |
| C.B. Transport Refrigeration Limited | Knowsley | 1987 |
| C.B.(Gunmakers) Limited | Bedford | 2006 |
| C.B.Eaton Joinery Ltd | Belper | 2015 |
| C.B.F. Screen Prints Limited | West Yorkshire | 1978 |
| C.B.Frost & Co Limited | Birmingham | 1948 |
| C.B.North (Timber) Limited | Hull | 2020 |
| C.B.North Limited | | 1937 |
| C.B.Tool Engineers (Cambridge) Limited | Peterborough | 1962 |
| C.Brand & Company(Estd 1868)LIMITED | Water Lane | 1953 |
| C.Brandauer & Co. Limited | | 1901 |
| C.C Equestrian, Pet & Farm Supplies Ltd | Dalton In Furness | 2025 |
| C.C Marine & Industrial Supply Limited | Segensworth West | 2003 |
| C.C Upholstery Ltd | Exeter | 2026 |
| C.C. Plant and Commercial Limited | Mexborough | 2017 |
| C.C.Moore & Co Limited | Sturminster Newton | 1958 |
| C.C.R.(Manufacturing) Ltd | London | 1997 |
| C.C.S. (Catercare) Limited | Amersham | 1995 |
| C.C.S. Engineering Company Limited | Irvine | 1974 |
| C.C.T. Limited | Chesterfield | 1989 |
| C.C.Warren Limited | Beaminster | 2013 |
| C.Contractors Ltd | Greenford | 2025 |
| C.Cripps & SON Limited | Middlesex | 1959 |
| C.D. Atkinson Engineering Company Limited | Warwickshire | 1981 |
| C.D. Bryant Limited | Portsmouth | 2003 |
| C.D. Electrical Services Limited | Carryduff | 2003 |
| C.D. Kitchens & Bedrooms Limited | Londonderry | 1997 |
| C.D. Services (Midlands) Limited | Walsall | 2006 |
| C.D.A. Retail Limited | Langar | 2000 |
| C.D.C. Heavy Textiles Limited | Wallasey | 1985 |
| C.D.D. Cable Specialists Limited | Redditch | 2013 |
| C.D.Glossop Ltd | Chesterfield | 2019 |
| C.D.L Carpentry Ltd | Newport | 2025 |
| C.D.M Decorative Glass and Conservatories Ltd | Ashton-Under-Lyne | 1997 |
| C.D.S. (NW) Limited | Altrincham | 2012 |
| C.D.S. Construction Services Limited | Slough | 1976 |
| C.D.S. Marine (Scotland) Ltd. | Glasgow | 2012 |
| C.D.S. Precision Engineering Limited | Blackpool | 2002 |
| C.D.Trading Ltd | Manchester | 2014 |