| A.S.K. & Co. Ltd | Birmingham | 2011 |
| A.S.K. Piearcey Limited | Weymouth | 2006 |
| A.S.K. Transport Solutions Limited | Camberley | 2012 |
| A.S.M. Engineering Trustees Limited | London | 2024 |
| A.S.Management Resources Ltd | Edinburgh | 2026 |
| A.S.Neill Summerhill CIC | Leiston | 2020 |
| A.S.P. Advisory Limited | London | 2015 |
| A.S.P.E. Limited | Barnstaple | 2002 |
| A.S.R PMO Limited | Dartmouth | 2023 |
| A.Sawyer Composites Ltd | Huntingdon | 2025 |
| A.Shah Associates Ltd | Westcliff On Sea | 2014 |
| A.SHAIKH2 Engineering Ltd | Huddersfield | 2025 |
| A.Sharp Construction Ltd | Newbury | 2023 |
| A.Sherwood Consultancy Ltd | Swansea | 2024 |
| A.Smith Planning & Control Limited | Derby | 2012 |
| A.T Kavanagh Consulting Ltd | Altrincham | 2022 |
| A.T Maile Limited | Welwyn | 2019 |
| A.T Power Services Ltd | Leicester | 2024 |
| A.T. Accountants & Co Limited | Ilford | 2009 |
| A.T. BIO Limited | Saffron Walden | 2024 |
| A.T. Brown Limited | Worcester | 2023 |
| A.T. Building Control Limited | Leigh On Sea | 2025 |
| A.T. Gilbertson Ltd | Dalkeith | 2018 |
| A.T. Harrison Limited | Birmingham | 1996 |
| A.T. Hendry Architect Limited | Ayr | 2022 |
| A.T. Mech Services Ltd | Nottingham | 2022 |
| A.T. Oliver & Sons Limited | Luton | 2004 |
| A.T. Smith/I.P.B. Services Limited | Worcestershire | 2006 |
| A.T.A Accounts & Management Limited | London | 2020 |
| A.T.A. Construction & Engineering Commercial Services Limited | Pickering | 2026 |
| A.T.C. Management Limited | Middlesex | 1991 |
| A.T.C. Property Limited | Barnsley | 1968 |
| A.T.E Sales and Marketing Ltd | Harpenden | 2009 |
| A.T.E. Trustee Limited | Basildon | 2024 |
| A.T.H Consulting Limited | London | 2011 |
| A.T.H Instruments Ltd | Stirling | 2006 |
| A.T.H. Consultancy Limited | Fareham | 2012 |
| A.T.J. Holdings Limited | Solihull | 1920 |
| A.T.Kearney Limited | London | 1968 |
| A.T.M. Strategic Management Consulting Limited | Leatherhead | 2000 |
| A.T.N. Property Ltd | London | 2003 |
| A.T.P. Advertising & Marketing Limited | Leeds | 1992 |
| A.T.Solutions (London) Ltd | Loughton | 2023 |
| A.Tan Consultancy Ltd | Tring | 2019 |
| A.U.H. Property Management Ltd | Birmingham | 2015 |
| A.V.A CAD Solutions Limited | Blackpool | 2016 |
| A.V.A.S Consultancy Limited | Leicester | 2016 |
| A.V.H. Property Company Limited | Iver | 2007 |
| A.V.P. Limited | Bridgwater | 1989 |
| A.V.Roe & Company Limited | Cleckheaton | 2009 |
| A.V.S. Accountancy Limited | Middlesex | 2000 |
| A.V.S. Designs Ltd | Kirkcaldy | 2022 |
| A.V.S.S Limited | Bracknell | 2006 |
| A.Vincent Solicitors Ltd | London | 2016 |
| A.W Consultancy & Engineering Services Limited | Shifnal | 2020 |
| A.W Engineering Consultancy Ltd | Wallsend | 2024 |
| A.W Safety Services Ltd | Jarrow | 2022 |
| A.W. Davis Properties Limited | Camberley | 1963 |
| A.W. Engineering (NW) Ltd | Chester | 2024 |
| A.W. Growth Solutions Ltd | Honiton | 2026 |
| A.W. Jenkinson (Forest Products) Limited | Penrith | 1995 |
| A.W. Mayhew (Farms) Limited | Ipswich | 1960 |
| A.W. Mellish Limited | Cambridge | 1982 |
| A.W. Perry & SON (Heating & Welding Engineers) Limited | | 1976 |
| A.W. Spring Limited | Tamworth | 2024 |
| A.W. Thorne Limited | Solihull | 1960 |
| A.W.(Pvt) Consulting Ltd | London | 2017 |
| A.W.A. Management Services Limited | Bolton | 1990 |
| A.W.E.S. Limited | Berkhamsted | 2000 |
| A.W.H Media Limited | Motherwell | 2021 |
| A.W.May.Limited | Brentwood | 1931 |
| A.W.Penton Developments Limited | Shropshire | 2002 |
| A.W.Q.A.T.S Limited | Benfleet | 2006 |
| A.W.S Mechanical Engineering Services Limited | Lymm | 2026 |
| A.W.Stokes & Sons Limited | Crawley | 2005 |
| A.W.Thomson & SON Limited | Sevenoaks | 2013 |
| A.Y Architecture Ltd | London | 2025 |
| A.Y. Developments Limited | Ashington | 2013 |
| A.Y. Sovereign Solicitors Ltd | Orpington | 2020 |
| A.Y.A Accountants Limited | Birmingham | 2011 |
| A.Y.A Investments Limited | Accrington | 2017 |
| A.Y.G.I. Limited | Bedford | 1994 |
| A.Y.O Accounting Solutions Limited | Altrincham | 2025 |
| A.Y.Suga Media Ltd | Luton | 2025 |
| A.Z.K. Design Office Limited | Radstock | 2017 |
| A.Z.R. Associates Ltd | Bury | 2015 |
| A/C Aviation Services Ltd | Saffron Walden | 2019 |
| A0 Design Studio Ltd | London | 2018 |
| A1 & Co Accountants Ltd | Leicester | 2021 |
| A1 Access Lifts Ltd | Keighley | 2021 |
| A1 Accountancy (London) Ltd | West Wickham | 2000 |
| A1 Accountancy and Business Services Ltd | Greater London, London | 2023 |
| A1 Accountancy Ltd | West Wickham | 2025 |
| A1 Accountancy Services Ltd | | 2003 |
| A1 Accountancy Solutions Ltd | Swansea | 2012 |
| A1 Accountants & Tax Advisors Limited | Downham Market | 2010 |
| A1 Accounting and Taxation Limited | Nantwich | 2022 |
| A1 Accounting Services Ltd | London | 2020 |
| A1 Accounting Solution Ltd | Blackpool | 2019 |
| A1 Accounting UK Limited | London | 2009 |