| A SQR UK Limited | Harlow | 2013 |
| A Square Solutions Limited | Slough | 2016 |
| A Squared Films Limited | Exeter | 2013 |
| A Squared Labs Limited | London | 2025 |
| A Squared Locations Limited | Belfast | 2025 |
| A Squared Projects Limited | Fordingbridge | 2024 |
| A Staley Solutions Ltd | Warwick | 2024 |
| A Star Communications Ltd | Welwyn Garden City | 2011 |
| A Star Consulting Ltd | Anerley | 2011 |
| A Star Forensics Ltd | Neath | 2011 |
| A Star Games Ltd | London | 2024 |
| A Star Key Services Ltd | Liphook | 2026 |
| A Star Productions Limited | Hayes | 2023 |
| A Starlight Production Ltd | Worthing | 2024 |
| A State of Change Ltd | Kington | 2019 |
| A Stellar Production Ltd | Macclesfield | 2012 |
| A Step FWD | Mildenhall | 2015 |
| A Step TOO FAR Productions Ltd | Chipping Norton | 2024 |
| A Stevanovic Limited | Reading | 2023 |
| A Stewart Consulting Ltd | Wimborne | 2018 |
| A Stitch in Timecode Ltd | London | 2014 |
| A Story Worth Telling Ltd | London | 2023 |
| A Stroke of Genius Limited | Newport | 2013 |
| A Styles Consulting Ltd | Waterlooville | 2024 |
| A Suitable Company Limited | London | 2018 |
| A Summer's Portrait Films Ltd | London | 2026 |
| A Sustainable Way Limited | London | 2021 |
| A SY Solutions Ltd | London | 2021 |
| A T Computer Consultants Limited | Curdworth, Sutton Coldfield | 2003 |
| A T Cook Limited | Birkenhead | 2003 |
| A T D Solutions Limited | Leeds | 2003 |
| A T Film & TV Rigging Ltd | Gravesend | 2020 |
| A T H Solutions (UK) Limited | County Durham | 2002 |
| A T Joseph Limited | Coventry | 2015 |
| A T Marton International Limited | Copthorne | 2019 |
| A T Proofreading Limited | Laughton | 2012 |
| A T W Software Services Limited | Cheltenham | 1986 |
| A T Whitelaw Consulting Ltd | Lanark | 2015 |
| A T.V. Aerial & Satellite Co Ltd | Whitley Bay | 2006 |
| A Table for Three Ltd | Woodford Green | 2024 |
| A Table for Two Ltd | Winchester | 2025 |
| A TAJ Consultancy Limited | Derby | 2021 |
| A Takhar Ltd | Leicester | 2024 |
| A Tale of Ltd | Pontyclun | 2023 |
| A Tall Story Ltd | Maidstone | 2019 |
| A TAP Away Ltd | Evesham | 2024 |
| A Taylor Engineering Services Ltd | Borehamwood | 2008 |
| A Teens. Thing Ltd | London | 2019 |
| A Testing Enterprise Limited | Nottingham | 2025 |
| A Thousand Cuts Limited | Leeds | 2019 |
| A Thousand Miles Ltd | Hillingdon | 2023 |
| A Thousand Projects Ltd | Hemel Hempstead | 2017 |
| A Thousand Tiny Cuts Limited | Bristol | 2013 |
| A Thousand Words Limited | Sandy | 2012 |
| A Time of Eagles Limited | Wirral | 2024 |
| A Time of Monsters Limited | Edgware | 2020 |
| A Tiny BIT Different Ltd | Stockport | 2021 |
| A to B Communications Limited | Beds | 2006 |
| A to B Connections Limited | Bury | 2014 |
| A to B IT Services Limited | Hertfordshire | 2004 |
| A to D Electronics Ltd | Basingstoke | 2013 |
| A to Exceptional Ltd | Newcastle Upon Tyne | 2026 |
| A to Play Ltd | Bath | 2016 |
| A to Z 4U Ltd | London | 2007 |
| A to Z Business Coachulting Ltd | Milton Keynes | 2024 |
| A to Z Electronic Enterprises Limited | Smethwick | 2025 |
| A to Z Farsi Limited | | 2004 |
| A to Z Film Production Ltd | West Bromwich | 2023 |
| A to Z Films Limited | Loughton | 2014 |
| A to Z IT Solution Limited | Leicester | 2025 |
| A to Z Media Management Limited | Harrow | 2014 |
| A to Z Productions Ltd | Sutton | 2024 |
| A Topiary Editing Ltd | London | 2015 |
| A Topping Rigging Ltd | Stockport | 2025 |
| A Touch of Code Limited | London | 2018 |
| A Touch of Joules CIC | Sheerness | 2025 |
| A Touch of Sienna Limited | Pinner | 2024 |
| A Town Consulting Ltd | Harrow | 2026 |
| A Tree in Bani Limited | London | 2021 |
| A Tribute to Life Ltd. | London | 2025 |
| A Turing Limited | Winchester | 2024 |
| A Turner Consulting Limited | Widnes | 2022 |
| A Ubhi & Co Limited | York | 2025 |
| A V Audio Limited | Boghead | 2018 |
| A V Consultancy Group Ltd | Horsham | 2021 |
| A V Digital Publishing Ltd. | Bristol | 1998 |
| A V Interactive Limited | Alcester | 1996 |
| A V Panto Limited | Luton | 2022 |
| A V Works Limited | Ryton | 2008 |
| A Venus Cultural Media Limited | Sheffield | 2025 |
| A Verify Solutions Limited | Buckingham | 2025 |
| A Vintage Co Ltd | Sheffield | 2013 |
| A Violet Tech Ltd | Watford | 2025 |
| A Virgo Limited | Sutton Coldfield | 2022 |
| A Visual by Benji Ltd | London | 2022 |
| A Vivid Sun Entertainment Ltd | Birmingham | 2024 |
| A Vlachos Brothers Productions Limited | Salford | 2025 |
| A Votre Service Limited | Caterham | 2003 |
| A W Bown Limited | Bournemouth | 2018 |
| A W Computers (UK) Limited | Birmingham | 2002 |