| A.Charles Capital Holdings Ltd | London | 2025 |
| A.D.A. Investment Management Limited | Southport | 1985 |
| A.D.D. Family Investments Ltd | Halifax | 2025 |
| A.D.F. Insurance Brokers Limited | Wolverhampton | 2007 |
| A.D.K Capital Ltd | London | 2025 |
| A.D.N. Financial Solutions Ltd | Portsmouth | 2008 |
| A.D.S. Insurance Brokers Limited | Colchester | 1988 |
| A.D.Woodley Limited | Gloucestershire | 1932 |
| A.E. and C.A. Wall Ltd. | Gosforth | 2012 |
| A.E. Chapman & Co (Holdings) Limited | Cradley Heath | 2025 |
| A.E. George and Sons Limited | Somerset | 1981 |
| A.E. Lenton (Holdings) Limited | Boston | 1961 |
| A.E. Mccandless (Shirt Makers) Limited | Londonderry | 2000 |
| A.E. Russell (Insurances) Limited | Coventry | 1961 |
| A.E. Spink (Holdings) Limited | Doncaster | 2024 |
| A.E.C Group Holding Limited | London | 2025 |
| A.E.HORDER(1963)LIMITED | Bristol | 1963 |
| A.E.Koole Beheer Limited | Doncaster | 2006 |
| A.E.S. Corporate Limited | Northampton | 2023 |
| A.F. Smith and SON (Group) Limited | Peterborough | 1952 |
| A.F. Switchgear (Holdings) Limited | Nottingham | 2007 |
| A.F.A. Limited | Sidcup | 1982 |
| A.F.K. (Holdings) Limited | Sleaford | 2017 |
| A.G Batiment Ltd | London | 2018 |
| A.G. Barr Capital Partner Limited | Glasgow | 2013 |
| A.G. Barr General Partner Limited | Glasgow | 2013 |
| A.G. Barr Pension Trustee Limited | Cumbernauld | 2013 |
| A.G. Thames 2019 Limited | Dartford | 2019 |
| A.G. Thames Investments Limited | London | 2019 |
| A.G.A.C Holdings Limited | Bourne | 2019 |
| A.G.S. (Steel Erectors) Holdings Limited | Coatbridge | 2024 |
| A.G.Wright(Assessors)Limited | Loughborough | 1961 |
| A.H. Construction Solutions Group Limited | London | 2021 |
| A.H. Willis and Sons Holdings Limited | Faringdon | 2015 |
| A.H.G Consultancy Ltd | Leatherhead | 2024 |
| A.Heads Holdings Ltd | Cramlington | 2021 |
| A.I. Assets Limited | London | 2016 |
| A.I. Choudhery Ltd | Luton | 2018 |
| A.I. Strategy Ltd | London | 2025 |
| A.I.A. Holdings Limited | Newcastle-Under-Lyme | 2025 |
| A.I.B.Nominees Limited | London | 1960 |
| A.I.J Property Limited | London | 2015 |
| A.I.L Holdings Limited | Knutsford | 2019 |
| A.I.L Packaging Holdings Limited | Knutsford | 2024 |
| A.I.M Capital Group Limited | Southampton | 2026 |
| A.I.Mills Ltd | Swansea | 2026 |
| A.I.S.N Limited | Stanmore | 2004 |
| A.I.Walgate & SON (Holdings) Limited | Lincs | 2016 |
| A.J. & M.A.Hardy Limited | Newport Pagnell | 1959 |
| A.J. Allen Frics Limited | Derby | 2008 |
| A.J. Baron (Holdings) Limited | Clitheroe | 2019 |
| A.J. Developments (Plymouth) Holdings Limited | Plymouth | 2023 |
| A.J. Distributors (Holdings) Limited | London | 2019 |
| A.J. Distributors (Investment Holdings) Limited | London | 2019 |
| A.J. Distributors (Investments) Limited | London | 2019 |
| A.J. Hassell Limited | Eastbourne | 1972 |
| A.J. Leese (Holdings) Ltd | Nantwich | 2024 |
| A.J. Lloyd Holdings Limited | Leamington Spa | 2016 |
| A.J. Maclean Ltd | Prestwick | 2018 |
| A.J. Options Limited | Motherwell | 2002 |
| A.J. Pies and Pastries (Group) Limited | Huddersfield | 2025 |
| A.J. Pies and Pastries (Holdings) Limited | Huddersfield | 2021 |
| A.J. Sharp Holdings Limited | Sheffield | 2018 |
| A.J. Wealth Management Limited | Wolverhampton | 2000 |
| A.J.Grayburn & Company Limited | Billericay | 1939 |
| A.J.M. Mansell Holdings Limited | Pinner | 2016 |
| A.J.Montgomerie Ltd | Skipton | 2022 |
| A.J.R. Financial Services (Scotland) Ltd. | Dunfermline | 2003 |
| A.J.S. (Stanton) Group Holdings Ltd | Willenhall | 2024 |
| A.J.S. Group 2020 Limited | Chorley | 2020 |
| A.J.S. Holdings Limited | Nottingham | 1999 |
| A.J.Saxton Holdings Limited | London | 2026 |
| A.K.A Holdings (Huddersfield) Ltd | Heckmondwike | 2023 |
| A.L. Ashway Limited | London | 1948 |
| A.L. Enterprises Ltd | London | 1993 |
| A.L. King (Holdings) Limited | Melksham | 2019 |
| A.L. Tozer Holdings Limited | Egham | 2024 |
| A.L.H. 86 Limited | London | 1986 |
| A.L.M. Products Holdings Limited | County Durham | 2018 |
| A.L.S. Autos Holdings Limited | Ely | 2021 |
| A.M Blatch Holdings Ltd | Wisbech | 2019 |
| A.M. Promech Ltd | Bury St. Edmunds | 2020 |
| A.M.A. Fennell Frics Limited | Norwich | 2008 |
| A.M.C Transport Solutions Holdings Limited | Belper | 2023 |
| A.M.L. Scaffolding (Holdings) Limited | Cardiff | 2016 |
| A.M.N.E Security Ltd | South Shields | 2025 |
| A.M.P Insurance Brokers Limited | Havant | 2018 |
| A.M.S. (Access Mortgage Solutions) Limited | Birmingham | 2013 |
| A.Matly Group Holdings Ltd | Preston | 2025 |
| A.Moore Holdings Limited | Salford | 2020 |
| A.Muja Limited | Reading | 2025 |
| A.N Financial Services Ltd | Slough | 2021 |
| A.N. Tools Limited | Warwickshire | 1999 |
| A.N.A. Associates Ltd | Brentford | 2007 |
| A.N.Y. UK Holdings Ltd | London | 2019 |
| A.P.C. Engineering Limited | Preston | 1999 |
| A.P.Last & Sons Limited | London | 1954 |
| A.P.R. Morris Limited | Castleford | 2020 |
| A.P.T. Financial Planning Limited | Dronfield | 2013 |
| A.Pepe Ltd | Liverpool | 2024 |