| A.D.V. Communications Limited | Kettering | 1992 |
| A.Dieperink Ltd | Petersfield | 2022 |
| A.E. Costin Haulage Limited | Leeds | 1975 |
| A.E.F. Productions Limited | London | 2022 |
| A.E.M. Installations Limited | Swindon | 2006 |
| A.Ego Ltd | Bury St. Edmunds | 2024 |
| A.Feki Ltd | London | 2016 |
| A.G. Film Fashion Limited | London | 2000 |
| A.G. Morgan Computer Services Limited | Carmarthenshire | 1999 |
| A.G. Sharepoint Solutions Ltd | Ivybridge | 2018 |
| A.G. Stage Ltd | London | 2023 |
| A.G. Strategic Partners Ltd | London | 2026 |
| A.G.A. Limited | Sheffield | 1997 |
| A.G.I. Mobile Communications Limited | Ely | 2006 |
| A.G.S. (Technology) Limited | | 2003 |
| A.G.S. Publications Limited | Pershore | 1979 |
| A.H Data Consultancy Ltd | Ilford | 2024 |
| A.H.P. Promotions Limited | Borehamwood | 1976 |
| A.H.P.Films Limited | Borehamwood | 1970 |
| A.I Robotics Ltd | London | 2020 |
| A.I Software Integration Limited | London | 2021 |
| A.I-Streamline Ltd | Grays | 2026 |
| A.I. Agents Ltd | Cambridge | 2017 |
| A.I. Editing Solutions Ltd | Northwood Hills | 2012 |
| A.I. Employee Ltd | Middlesbrough | 2025 |
| A.I. Global Media Limited | Burton-On-Trent | 2010 |
| A.I. Media Limited | Middlesex | 2002 |
| A.I. Reports Ltd | London | 2025 |
| A.I. Springs Limited | Swanscombe | 2020 |
| A.I. Talent Ltd | York | 2003 |
| A.I. UN Limited | Bolton | 2019 |
| A.I. Videomatics Ltd | Croydon | 2022 |
| A.I.C.G Ltd | Macclesfield | 2016 |
| A.I.Cold Ltd | London | 2025 |
| A.I.Conic Ltd | Buckingham | 2026 |
| A.I.Film Production Limited | London | 2013 |
| A.I.H. (Stranraer) Ltd | Stranraer | 2023 |
| A.I.Motivate C.I.C. | Nottingham | 2025 |
| A.I.Q. Limited | Surbiton | 1984 |
| A.I.R Edel Associates Limited | London | 1970 |
| A.I.R.-Edel Recording Studios Limited | London | 1952 |
| A.Ideal Group Limited | Edinburgh | 2025 |
| A.J Civils Engineering Ltd | Liverpool | 2019 |
| A.J Software Consulting Services Limited | Welling | 2011 |
| A.J Technologies Limited | Southampton | 2025 |
| A.J-It Support Ltd | London | 2015 |
| A.J. Baker Ltd | Holme Hale | 2012 |
| A.J. Communications Limited | Chelmsford | 1998 |
| A.J. Curtis Limited | Lincs | 2006 |
| A.J. Davidson Limited | Kenilworth | 2000 |
| A.J. Lowe Limited | Essex | 1987 |
| A.J. Mcleay Ltd | Brighton | 2012 |
| A.J.B. Design Projects Limited | Liskeard | 1987 |
| A.J.K. Limited | West Yorkshire | 1997 |
| A.J.Lockwood Limited | Rochford | 2024 |
| A.J.Nicholls & SON Limited | Dudley | 2003 |
| A.J.R TV Ltd | Rotherham | 2022 |
| A.J.S. Boyne and Co. Ltd | Brighton | 2024 |
| A.J.S. Contract Design Limited | Wormhill | 1998 |
| A.J.V. Computing Ltd | Dorset | 1999 |
| A.K Abba IT Solutions Ltd | Leicester | 2019 |
| A.K. Robinson Limited | Modbury | 2005 |
| A.K.A. Vision Ltd | Reigate | 2015 |
| A.K.S Online Consultancy Ltd | London | 2024 |
| A.K.Systech Ltd | London | 2025 |
| A.K.T. Associates Limited | Macclesfield | 2002 |
| A.L. Media Ltd | London | 2015 |
| A.L.E. Digital & Media Production Limited | Leeds | 2021 |
| A.L.E. Marine Limited | Newcastle Upon Tyne | 1987 |
| A.L.F. Office Solutions Ltd | Harpenden | 2006 |
| A.L.F. Productions Limited | Tring | 1999 |
| A.L.R. Rigging Ltd | St Albans | 2015 |
| A.L.T. Records Ltd. | Battle | 1995 |
| A.M Analytics Ltd | London | 2024 |
| A.M I.T. Integration Consulting Ltd. | Stamford | 2022 |
| A.M Locations Ltd | Farnham | 2025 |
| A.M Produktions Ltd | London | 2025 |
| A.M Visual Productions Ltd | London | 2025 |
| A.M. Analytics Incorporated Limited | Bury St. Edmunds | 2025 |
| A.M. Best Europe - Information Services Limited | London | 2010 |
| A.M. Data Solutions Limited | Lichfield | 2024 |
| A.M.A. Technology Limited | Nr Bordon | 1997 |
| A.M.C. Recordings Limited | York | 2010 |
| A.M.Heath & Company Limited | | 1921 |
| A.M.I.A. Group International Ltd. | Cardiff | 2020 |
| A.M.J.D Consulting Ltd | Grays | 2019 |
| A.M.L.E IT Consultancy Ltd | London | 2023 |
| A.M.U Ltd | Rochdale | 2019 |
| A.M.Visuals Ltd | Batley | 2025 |
| A.Mohameditconsultancy Ltd | London | 2025 |
| A.Moore Software Limited | Salford | 2026 |
| A.Mushtaq Ltd. | Ossett | 2017 |
| A.N. Computing Limited | Liverpool | 1999 |
| A.N. Telecom (U.K.) Ltd | London | 1999 |
| A.N.D Sovereign Group UK Limited | London | 2026 |
| A.N.E. Consultancy Services Ltd | Ringwood | 2019 |
| A.N.R. Associates Limited | York | 1994 |
| A.N.T Incorporated Limited | Somerset | 2022 |
| A.N.T Publishing Limited | London | 2006 |
| A.N.T. Aerials & Satellites Ltd | Newport | 2006 |