| Clarkes Sparks Ltd | Uxbridge | 2021 |
| Clarkeshaws Limited | Chesterfield | 2025 |
| Clarkey's Cider UK Ltd | Sutton Coldfield | 2025 |
| Clarkin Electronics Limited | Workington | 2002 |
| Clarking Interiors Ltd | Doncaster | 2024 |
| Clarks Glass & Glazing Limited | Ringmer | 2002 |
| Clarks Glass Limited | Salisbury | 2025 |
| Clarks Independence Centre Ltd | Leeds | 2011 |
| Clarks of Bristol Ltd | Bristol | 2022 |
| Clarks Pies Limited | Bristol | 2002 |
| Clarks Technology Solutions Limited | Doncaster | 2022 |
| Clarks Vehicle Conversions Limited | Doncaster | 1999 |
| Clarks(Wantage),Limited | Oxford | 1908 |
| Clarkshaws Brewing Company Ltd. | London | 2013 |
| Clarkson Carpentry Services Ltd | Cardiff | 2018 |
| Clarkson Coatings Limited | Brighouse | 2022 |
| Clarkson Controls Limited | Belbroughton | 1982 |
| Clarkson Dairy Services Limited | Leyburn | 2001 |
| Clarkson Joinery & Furniture Ltd | Tunbridge Wells | 2013 |
| Clarkson Marine Limited | Bridgend | 2010 |
| Clarkson Retail Limited | Hull | 2009 |
| Clarkson Security Ltd | Leeds | 2013 |
| Clarkson Services Limited | Hull | 1996 |
| Clarkson Textiles Limited | Nelson | 1983 |
| Clarkson-Paul Carpentry & Electrical Ltd | Chichester | 2024 |
| Clarksteel Holdings Limited | Peterborough | 1971 |
| Clarkston Services Ltd. | Glasgow | 2005 |
| Clarktec Systems Limited | Glasgow | 2022 |
| Clarkway Mechanical Services Limited | Dukinfield | 2015 |
| Clarkwood Engineering Limited | Blakenhall | 1975 |
| Clarky Consulting Limited | Derby | 2022 |
| Clark’S Carpentry Limited | Hailsham | 2025 |
| Clarmac Engineering Company Limited | 26 West Nile Street | 1928 |
| Clarman Joinery (Lincoln) Ltd | Lincoln | 2008 |
| Claro Hookeye Limited | Blackwood | 1942 |
| Claro Hookeye Services Limited | Blackwood | 1972 |
| Claro Precision Engineering Limited | Knaresborough | 2024 |
| Claromech Limited | Perth | 2007 |
| Claron (Plastics) Limited | Paignton | 1984 |
| Claron Hydraulic Seals Limited | Wolverhampton | 1975 |
| Claron Limited | Paignton | 2008 |
| Clarornell Consulting and Trading Ltd | London | 2011 |
| Clartes Ltd | Colchester | 2010 |
| Clarus Skin Ltd | Glasgow | 2021 |
| Clarvan Plastics Ltd | Fintona | 2014 |
| Clary & PEG Limited | London | 2012 |
| Clarydon Electronic Services Limited | Birmingham | 1997 |
| Claryon Group Ltd | London | 2025 |
| Clas Engineering Solutions Ltd | Mildenhall | 2026 |
| Clas-Sic Wafer FAB Limited | Lochgelly | 2017 |
| Clasado Limited | Reading | 2004 |
| Clash Energy Services Ltd | Weston-Super-Mare | 2018 |
| Clashaig Repairs Ltd | Halkirk | 2024 |
| Class 1 Logistics Ltd | Umberleigh | 2024 |
| Class 507 Preservation Ltd | Liverpool | 2024 |
| Class 58 Locomotives Ltd | Reading | 2010 |
| Class a Audio Ltd | Sheffield | 2019 |
| Class a Cakes Ltd | Luton | 2020 |
| Class Carpentry Contractors Ltd | Hemel Hempstead | 2023 |
| Class Delta Ltd | Liverpool | 2012 |
| Class Fundraising Limited | Stockton-On-Tees | 2010 |
| Class G5 Locomotive Company Ltd | Shildon | 2007 |
| Class Instrumentation Ltd | | 1996 |
| Class J Electronics Limited | Finchley | 2011 |
| Class Labels Limited | London | 2023 |
| Class One Meat & Poultry Limited | Bradford | 2021 |
| Class One Truck Repairs Limited | Chertsey | 2009 |
| Class Scents Ltd | Airdrie | 2026 |
| Class Trade Solutions Ltd | Ayr | 2023 |
| Class Two Truck Repairs Limited | Chertsey | 2023 |
| Class Workwear Limited | Uxbridge | 2018 |
| Classeq Limited | Stafford | 1980 |
| Classer Ltd | Cwmbran | 2024 |
| Classic & Prototype Panels Limited | Warwickshire | 2007 |
| Classic -Tropical Foods Ltd | Glasgow | 2024 |
| Classic Acoustics Limited | Telford | 1998 |
| Classic Airstreams Ltd | London | 2024 |
| Classic and Retro Limited | Colchester | 2012 |
| Classic Arcades Ltd | Henfield | 2013 |
| Classic Art Pictures Limited | Manchester | 1985 |
| Classic Audio Ltd | Gillingham | 2020 |
| Classic Bedrooms Limited | Wigston | 2012 |
| Classic Beds (UK) Ltd | Dewsbury | 2012 |
| Classic Blinds Wales Ltd | Porth | 2008 |
| Classic Boat Restorations Limited | Cowes | 2000 |
| Classic Building & Flooring Specialist Limited | Westcliff-On-Sea | 2015 |
| Classic Business Forms Limited | Sheffield | 1992 |
| Classic Business Products Limited | Sheffield | 2016 |
| Classic Cabinetry Designs Ltd | Ilford | 2020 |
| Classic Cabinetry Limited | West Horndon | 2016 |
| Classic Candle Company Ltd | Leighton Buzzard | 2014 |
| Classic Car Trim Products Ltd | Bodmin | 2010 |
| Classic Carbon Limited | Bury St. Edmunds | 2011 |
| Classic Carbs UK Ltd | Brierley Hill | 2024 |
| Classic Cars of Kent Limited | Seaford | 1997 |
| Classic Chassis Services Limited | Leighton Buzzard | 2007 |
| Classic Colours Limited | Reading | 1989 |
| Classic Conservatory Systems Limited | Blackburn | 2002 |
| Classic Continuous Limited | Sutton Coldfield | 1987 |
| Classic Creations (NW) Ltd | Chorley | 2026 |