| A Star Services Ltd | London | 2015 |
| A Star Solutions Ltd | London | 2018 |
| A Star Studios Limited | London | 2007 |
| A Star Support Group Ltd | Holywell | 2018 |
| A Star TQS Training Limited | Downend | 2012 |
| A Star Training Solutions Ltd | Beverley | 2010 |
| A Step Forward Limited | London | 1997 |
| A Step Limited | Tetbury | 2015 |
| A Stevenson Services Limited | Kirkcaldy | 2024 |
| A Stewart Interior Limited | Marlow | 2007 |
| A Stokes & Co Limited | Stanfree | 2017 |
| A Story Called Limited | Bury | 2013 |
| A Story in Motion Studios Ltd | Leeds | 2026 |
| A Stott Financial Planning Ltd | Sowerby Bridge | 2019 |
| A Stow Engineering Ltd | Milford Haven | 2023 |
| A Studio Between Ltd | London | 2022 |
| A Studio Called Jane Ltd | Urmston | 2019 |
| A Studio Limited | London | 2006 |
| A Studio of OUR Own Limited | Worcester Park | 2016 |
| A Style LAB Co Limited | Ipswich | 2022 |
| A Sullivan Accountants Limited | Newton Abbot | 2023 |
| A Surveying Limited | Chelmsford | 2023 |
| A Sutherland Design Ltd | Dunfermline | 2019 |
| A Sutton Limited | St. Albans | 2009 |
| A Suwareh Accountancy Ltd | Dagenham | 2014 |
| A Swann Consulting Ltd | London | 2024 |
| A Syed & Co Limited | Beverley | 1997 |
| A T & J Training and Development Ltd | Bedford | 2006 |
| A T a Sunrays Limited | London | 2006 |
| A T and Co Accountants Ltd | Coventry | 2016 |
| A T Business Support Ltd | Leek | 2023 |
| A T C (Blackwell) Ltd | Stafford | 2002 |
| A T Cladding Consultants Ltd | Brigg | 2013 |
| A T Communications Europe Limited | Tamworth | 1995 |
| A T Fire Consultancy Limited | Preston | 2017 |
| A T Gilchrist Consulting Ltd | Liphook | 2017 |
| A T I Services Limited | Leeds | 2021 |
| A T Jones Consultancy Ltd | Swansea | 2018 |
| A T Lift Services (Kent) Ltd | Bromley | 2011 |
| A T New Media Limited | Poole | 2005 |
| A T P Turbines Limited | Wetherby | 2011 |
| A T S 3 Limited | Harrow | 2019 |
| A T S a I Limited | London | 2020 |
| A T S Project Solutions Ltd | Barnet | 2018 |
| A T S S Limited | Marlborough | 2005 |
| A T S Services Limited | London | 1997 |
| A T Sprayer Solutions Ltd | Alford | 2023 |
| A T Taylor Inspection Services Limited | Glossop | 2013 |
| A T Valuations Ltd. | Harrow | 2022 |
| A T Walsh Limited | Glasgow | 2009 |
| A T Williams Ltd | Brighton | 2017 |
| A T Z Event Safety Limited | Stoughton | 2022 |
| A TAD Over One Stone Tungsten Projects Limited | Lancaster | 2017 |
| A Taigh Chon Ltd | Knottingley | 2023 |
| A Tall Long Legged Bird Limited | Trowbridge | 2026 |
| A Tavola Consulting Ltd | London | 2023 |
| A Tavola Limited | London | 2009 |
| A Taylor Design Ltd | Gerrards Cross | 2024 |
| A Taylor Offshore Limited | North Shields | 2026 |
| A Taylor-Bird Ltd | Brighton | 2023 |
| A Taylored Solution Limited | Epsom | 2013 |
| A Team Advisory Limited | London | 2026 |
| A Team Finance Limited | London | 2011 |
| A Team Marketing Ltd | Harrogate | 2012 |
| A Team Projected Limited | London | 2016 |
| A Thakur Limited | Northampton | 2012 |
| A Theodore Company Ltd | Blackpool | 2023 |
| A Thin Line Between Ltd | Dartford | 2022 |
| A Think Labs Ltd | London | 2019 |
| A Thinking Space Ltd | Sudbury | 2010 |
| A Thomas QA Services Ltd | Salisbury | 2019 |
| A Thomson Consulting Ltd | Andover | 2025 |
| A Thomson Engineering Ltd | Bishop Auckland | 2013 |
| A Thousand Decisions Ltd | London | 2022 |
| A Thousand Monkeys EOT Ltd | Chandler'S Ford | 2024 |
| A Thousand Words Photography Ltd | Kendal | 2021 |
| A Thousand Words Visuals Ltd | Waltham Abbey | 2023 |
| A Thousand Years Limited | Nuneaton | 2022 |
| A Thyme to Gather Ltd | Taunton | 2025 |
| A Tiny Horse Ltd | Southend-On-Sea | 2022 |
| A to a Design Consultancy Ltd | Newport | 2014 |
| A to B Digital Marketing Ltd | Llandudno | 2017 |
| A to B Direct Holdings Ltd | Nottingham | 2022 |
| A to B Holdings Limited | Doncaster | 2009 |
| A to G Energy Assessments Limited | Staffordshire | 2007 |
| A to MEE Ltd | Leicester | 2020 |
| A to There Solutions Ltd | London | 2016 |
| A to Z Academy International Ltd | London | 2024 |
| A to Z Accountancy Services Limited | London | 2023 |
| A to Z Accountants Limited | Orpington | 2009 |
| A to Z Accounting and Bookkeeping Limited | High Wycombe | 2017 |
| A to Z Advisory Ltd | Harrow | 2024 |
| A to Z BIZ Solutions Limited | Birmingham | 2020 |
| A to Z Book-Keeping Services Limited | Warwickshire | 2002 |
| A to Z Bookkeeping Ltd | Glasgow | 2024 |
| A to Z Business Consultants Limited | London | 2026 |
| A to Z Communications and Strategy Ltd | London | 2020 |
| A to Z Education Ltd | London | 2019 |
| A to Z General Management Limited | Arkley | 2026 |
| A to Z Holdings Limited | Tenbury Wells | 2008 |