| Aquatic Passions Ltd | Milton Keynes | 2019 |
| Aquatic Remedies Limited | Borehamwood | 2024 |
| Aquatic Specialist Services Ltd | Swansea | 2016 |
| Aquatic Specialist Wimborne Limited | Swansea | 2024 |
| Aquatic Supplies and Services Wales Ltd | Swansea | 2014 |
| Aquatics Limited | Eastbourne | 1996 |
| Aquaxprs Ltd | Cambridge | 2015 |
| Aquetong Farming Limited | Chippenham | 2003 |
| Aquila Corporation UK Limited | Swindon | 1999 |
| Aquila Investments Limited | Cambridge | 1991 |
| Aquila Lakes Limited | Kettering | 2022 |
| Aquila Shellfish Ltd | Stornoway | 2025 |
| Aquila Sporthorses Limited | Pontefract | 2012 |
| Aquoprotein Ltd | Ely | 2020 |
| AR & D Laughton Limited | Louth | 2015 |
| AR Farming Ltd | Rochester | 2020 |
| AR Hooper and Partners Ltd | Crediton | 2014 |
| AR Owen Power Services Limited | Corwen | 2006 |
| AR Walks Ltd | Crewe | 2024 |
| Arab-Global Investors Alliences Ltd | London | 2025 |
| Arabexchange Ltd | London | 2025 |
| Arabians Unlimited Limited | Stockport | 2018 |
| Arable Alliance Limited | Lincoln | 2009 |
| Arable Crops Ltd | Selby | 2013 |
| Arable Farm Contractors Limited | Grantham | 2016 |
| Arable Ventures Ltd | Kirriemuir | 2014 |
| Arable Z Limited | 138-141 Redcliff Street Bristol | 1903 |
| Aracon Farming Limited | Liverpool | 2004 |
| Aral Growers CIC | Newquay | 2024 |
| Aramor Ltd. | Aberdeenshire | 2003 |
| Aran Vale Products Limited | Hereford | 2008 |
| Aranatha Fishing Ltd. | Buckie | 2017 |
| Araucaria Fine Foods Ltd | York | 2019 |
| Arazi Limited | Cardiff | 2014 |
| ARB ( Tree Care Specialists ) Limited | Stoke-On-Trent | 2002 |
| ARB Aspire Tree Care Ltd | Haslemere | 2016 |
| ARB Central Ltd | Stourbridge | 2026 |
| ARB Clear Limited | Penrith | 2020 |
| ARB Consultancy Trees Limited | Dorking | 2014 |
| ARB Consultants Ltd | Preston | 2007 |
| ARB East Tree Services Limited | Woodbridge | 2017 |
| ARB Force 1 Ltd | Castell-Nedd | 2026 |
| ARB Forestry Limited | Rye | 2015 |
| ARB Giant Ltd | Caernarfon | 2024 |
| ARB Group Services Limited | Bewdley | 2022 |
| ARB Holdings Northwest Ltd | Bolton | 2025 |
| ARB Hunter Limited | Dorchester | 2025 |
| ARB Rangers Ltd | Chichester | 2025 |
| ARB Resolutions Limited | Taunton | 2021 |
| Arb-Core Tree Care Limited | Spalding | 2006 |
| Arb-Solute Tree Management Limited | Romsey | 2022 |
| Arbagri Ltd | Neath | 2024 |
| Arbanmore Ltd. | Northumberland | 2016 |
| Arbaware Tree Care Ltd | Alton | 2022 |
| Arbcology Ltd | Taunton | 2025 |
| Arbcore Ltd. | Aberystwyth | 2012 |
| Arbculture Ltd | Caldicot | 2022 |
| Arbcymru Ltd | Bridgend | 2015 |
| Arbdirect Ltd | Macclesfield | 2023 |
| Arberi Limited | Radstock | 2022 |
| Arbfocus Ltd | Llanrhystud | 2022 |
| Arbgear Ltd | Bromsgrove | 2019 |
| Arbility Ltd | Gillingham | 2019 |
| Arbland Ltd | Tiverton | 2021 |
| Arbology Tree Care Ltd | St. Helens | 2026 |
| Arbor Agricultural Services Ltd | Thetford | 2013 |
| Arbor Agriculture Limited | Stanmore | 2017 |
| Arbor Care Tree Services (South East) Limited | Brentwood | 2008 |
| Arbor Cura Tree Surgery Limited | Haywards Heath | 2012 |
| Arbor Division Ltd | Seaham | 2006 |
| Arbor Environmental Ltd | Richmond | 2021 |
| Arbor Farm UK Limited | Tintagel | 2020 |
| Arbor Services Limited | Bridgwater | 2016 |
| Arbor Tree Specialists Ltd | Oxford | 2017 |
| Arbor Tree Surgery Ltd | Rye | 2018 |
| Arbor Venture Tree Care Ltd | Lymington | 2019 |
| Arbor Vitae Environment Limited | Shropshire | 2007 |
| Arbora Arborists Limited | Amersham | 2025 |
| Arborcare (UK) Limited | Ferndown | 2006 |
| Arborcare Services Ltd | Hull | 2022 |
| Arborcare Tree Surgery (U.K.) Ltd | Norwich | 2026 |
| Arborcare Tree Surgery Ltd | Staffordshire | 2003 |
| Arborchase Limited | Stone | 2017 |
| Arborcraft Ltd | Gloucester | 2019 |
| Arborculture Ltd | Crymych | 2016 |
| Arborcure Limited | Plymouth | 2013 |
| Arborcut Tree Services Limited | Leyburn | 2010 |
| Arboreal Associates Limited | Stowmarket | 2026 |
| Arboreal Innovations Ltd | London | 2014 |
| Arboreal Limited | Bath | 2024 |
| Arboreal Tree Care Ltd | Lechlade | 2024 |
| Arboreal Tree Services Ltd | Saundersfoot | 2026 |
| Arboreal Woodlands Ltd | Chichester | 2023 |
| Arboreco Limited | Leicester | 2012 |
| Arboretum Estates Limited | Dunbar | 2008 |
| Arboretum Internationale Limited | Perth | 1997 |
| Arborex Ltd | Sherborne | 2019 |
| Arborex Tree Specialists Ltd | Nottingham | 2017 |
| Arborez Ltd | Lincoln | 2019 |
| Arborflight Ltd | London | 2016 |