| A.C. 2000 (UK) Limited | Northumberland | 1999 |
| A.C. Appointments Limited | Ashford | 1966 |
| A.C. Beck Holdings Limited | Wokingham | 2014 |
| A.C. Compliance Ltd | Newport | 2018 |
| A.C. Cooper (Colour) Limited | London | 1960 |
| A.C. Cooper Limited | London | 2013 |
| A.C. Creative Photography Limited | Colchester | 2002 |
| A.C. Directors Limited | Hertford | 2001 |
| A.C. Egerton (Holdings) Limited | Dartford | 1964 |
| A.C. Financial Management Solutions Ltd | Enfield | 2025 |
| A.C. HR Solutions Limited | Harpenden | 2013 |
| A.C. Lighting (Overseas) Limited | High Wycombe | 2002 |
| A.C. Nielsen Company Limited | Oxford | 1996 |
| A.C. Secretaries Limited | Hertford | 2001 |
| A.C. Sheet Metal Design Ltd | Weldon | 2023 |
| A.C. Survey Services Limited | Dundee | 1991 |
| A.C. Worldwide Group Limited | High Wycombe | 2002 |
| A.C.A Global Infrastructure Ltd | Nottingham | 2026 |
| A.C.A. Heya Sprouts Ltd. | London | 2017 |
| A.C.A. Management Services Limited | London | 1994 |
| A.C.C. Associates (Export) Limited | London | 1954 |
| A.C.C. Engineering Ltd | Kenley | 2008 |
| A.C.C. Worldwide Limited | London | 2006 |
| A.C.D. Taxis Ltd. | | 2001 |
| A.C.E. (Assessors) Ltd | | 1993 |
| A.C.E. (Stonehaven) Limited | | 1990 |
| A.C.E. Architectural Services Limited | Ballymena | 2020 |
| A.C.E.L.M Ltd | Basildon | 2023 |
| A.C.E.Rogan (Consultancy) Ltd | Craigavon | 2007 |
| A.C.F. Consulting Limited | New Mills High Peak | 1996 |
| A.C.G.S. Limited | Bridlington | 2004 |
| A.C.Guy - Building Envelope Solutions Limited | Kingswinford | 2014 |
| A.C.Guy Glazing Design Limited | Kingswinford | 2025 |
| A.C.H. Holdings Kent Ltd | West Malling | 2016 |
| A.C.J.R. Limited | Malton | 2017 |
| A.C.N. International Limited | Glasgow | 2005 |
| A.C.S. Employment Limited | Altrincham | 2018 |
| A.C.S. Properties Limited | Kirkby | 2006 |
| A.C.S.L. Ltd | Liverpool | 2008 |
| A.C.Smith Technical Services Ltd | West Midlands | 2013 |
| A.C.T Quantity Surveying Limited | St Ives | 2010 |
| A.C.T. (National) Ltd | Walsall | 2000 |
| A.C.T. Audit Limited | London | 2016 |
| A.C.T. Capital Advisers Limited | London | 2018 |
| A.C.T. Consultant Services Limited | Horsham | 2019 |
| A.C.T. Developments Ltd | London | 2010 |
| A.C.T. Financial Services Ltd | Newport | 2003 |
| A.C.T. Garage Equipment Limited | Laughton | 2008 |
| A.C.T. London Limited | London | 2002 |
| A.C.T.S Global Ltd | London | 2010 |
| A.Clarke Design Ltd | Cheltenham | 2016 |
| A.D & JO Consultancy Limited | London | 2026 |
| A.D Accounting Solutions Ltd | London | 2021 |
| A.D Autos Service Centre Ltd | Sittingbourne | 2025 |
| A.D Management Services Limited | Leicester | 2022 |
| A.D Safety Ltd | Middlesbrough | 2026 |
| A.D. Coates & Co Ltd | Edinburgh | 2006 |
| A.D. Creative Consultants Limited | London | 1973 |
| A.D. Direction Limited | Redditch | 2019 |
| A.D. Draughting Limited | Marlborough | 2016 |
| A.D. Drawing Services Limited | Loughborough | 2011 |
| A.D. Fabrication & Mechanical Services Limited | Elgin | 2021 |
| A.D. Hewitt Ltd | Swanage | 2005 |
| A.D. Horner Limited | Havant | 1996 |
| A.D. Ibbitson Consulting and Interim Limited | Nuneaton | 2018 |
| A.D. Jarman Limited | Blackpool | 2020 |
| A.D. Land Consultancy Limited | Derby | 2006 |
| A.D. Maclean Ltd. | Glasgow | 2010 |
| A.D. Norman Ltd. | Dunblane | 1995 |
| A.D. Pottie & Co Ltd | Fintona | 2007 |
| A.D. Practice Limited | Stevenage | 2002 |
| A.D. Services and Solutions Ltd | London | 2020 |
| A.D. Sheen Design Limited | Northwich | 1996 |
| A.D. Shielding Solutions Limited | Royston | 2018 |
| A.D. Surveyors Ltd | | 2003 |
| A.D.A Construction Consultants Ltd | Paisley | 2014 |
| A.D.A. Business Management & Bookkeeping Services Ltd | Nuneaton | 2021 |
| A.D.B Management & Consultancy Ltd | Newton Aycliffe | 2019 |
| A.D.B Project Consulting Limited | Chorley | 2012 |
| A.D.Communications Limited | Esher | 1984 |
| A.D.E ( South London ) Ltd | Sittingbourne | 2014 |
| A.D.E Machining Services Limited | Cannock | 2012 |
| A.D.E Surveyors Limited | Cheadle | 2023 |
| A.D.E. Accountancy Limited | Burntwood | 2012 |
| A.D.G. Consultancy Limited | Plymouth | 1998 |
| A.D.H. Design Limited | Plymouth | 1994 |
| A.D.L.Z. (Benussi) Limited | Cannock | 2012 |
| A.D.N. Legal Consultant Limited | Clayhall | 2018 |
| A.D.R. (Business Services) Limited | Hartlepool | 1991 |
| A.D.S. Advertising & Design (Oxford) Limited | Combe | 1988 |
| A.D.S. Associates Ltd. | Maidstone | 2002 |
| A.D.S. Engineering Limited | Renfrew | 1993 |
| A.D.S. Holdings Limited | Warrington | 1999 |
| A.Dicken & Son(Tees-Side)Limited | Chandlers Ford Eastleigh | 1959 |
| A.Djedjeia Ltd | London | 2025 |
| A.Downes Safety Services Ltd | Middlesbrough | 2016 |
| A.E Business Solutions Ltd | Llysfaen | 2024 |
| A.E. Adams (Holdings) Limited | Lancing | 2007 |
| A.E. Beckett & Sons (Espanola) Limited | Birmingham | 1965 |
| A.E. Brown (Holdings) Limited | Newport | 2021 |