| Altitec Limited | Maidstone | 2001 |
| Altitude Coffee Ltd | Hornchurch | 2020 |
| Altitude Engineering Limited | Chelmsford | 2020 |
| Altitude Glass Ltd | Blackburn | 2023 |
| Altitude Professionals Ltd | Hyde | 2023 |
| Altitude Roofs Limited | St Austell | 2020 |
| Altitude Weldtech Services Ltd | Hartlepool | 2014 |
| Altius Lifts Ltd | Marple | 2026 |
| Altivex Performance Ltd | Feltham | 2025 |
| Altix Lifts Limited | Barking | 2025 |
| Altkuz Climate Renewables LLC Ltd | Mildenhall | 2024 |
| Alto Bollards (Newcastle) Limited | Newcastle Upon Tyne | 2013 |
| Alto Dynamics Ltd | Hereford | 2024 |
| Alto Engineering Limited | Newcastle Upon Tyne | 1971 |
| Alto Seating Systems Limited | Birmingham | 1995 |
| Alto Systems Limited | Birmingham | 2005 |
| Alto Tower Systems Limited | Birmingham | 2000 |
| Altogether Ginger Ltd | Croydon | 2022 |
| Altomed Limited | Toddington | 1976 |
| Alton Beverages Limited | London | 2025 |
| Alton Cars Limited | Leeds | 1979 |
| Alton Compressor Services Ltd | Fareham | 2019 |
| Alton Precision Engineering Limited | Longport Stoke On Trent | 1987 |
| Alton Pumps Ltd | Liphook | 2026 |
| Alton Stahl Ltd | London | 2022 |
| Altone Limited | Stansted | 2001 |
| Altorra Group Ltd | London | 2025 |
| Altos Medical Ltd | London | 2012 |
| Altovolo Ltd | Gerrards Cross | 2026 |
| Altrac Living Limited | Middlesbrough | 2020 |
| Altrad Babcock Energy Services (Overseas) Limited | Warrington | 1968 |
| Altrad Babcock Limited | Warrington | 1965 |
| Altrad Babcock Power Systems Overseas Investments Limited | Warrington | 1996 |
| Altrad Belle Limited | Nr Buxton | 2016 |
| Altrad Engineering Services Limited | Warrington | 1994 |
| Altrad NSG Limited | Warrington | 2010 |
| Altrans Liquids Limited | Nr. Dursley | 1988 |
| Altratech Limited | Macclesfield | 2001 |
| Altraventis Ltd | London | 2026 |
| Altrech Limited | Carlisle | 1993 |
| Altric Limited | Lincoln | 1985 |
| Altrincham Glass Company Limited | Altrincham | 1975 |
| Altrincham Home Solutions Limited | Altrincham | 2019 |
| Altro Limited | Hertfordshire | 1919 |
| Altro Photonics Ltd | London | 2026 |
| Altron Communications Equipment Limited | Ammanford | 1971 |
| Altron Manufacturing and Engineering Limited | Ammanford | 2001 |
| Altros Engineering Limited | High Wycombe | 1992 |
| Altu Technology Limited | Bristol | 2016 |
| Altuk Limited | Weston-Super-Mare | 2022 |
| Altum Aviation Maintenance Ltd | Solihull | 2025 |
| Altum Designs Ltd | Bristol | 2015 |
| Altun Electronic Ltd | London | 2021 |
| Altura Lifts Ltd | London | 2024 |
| Alturos Health Limited | London | 2022 |
| Altus Controls Limited | Lutterworth | 2020 |
| Altus Group Ltd | Redditch | 2001 |
| Altus Science Limited | Runcorn | 2011 |
| Altus Shopfitters Ltd | Ashford | 2021 |
| Altwood Bespoke Ltd | Addlestone | 2018 |
| Altyd Limited | London | 2021 |
| Alt’S Builders Limited | Sidcup | 2024 |
| ALU & Glass Services Limited | Sheffield | 2026 |
| ALU Fold and Slide Ltd | Hebden Bridge | 2023 |
| ALU GID Ltd | Edinburgh | 2020 |
| ALU Pro (South Wales) Limited | Caldicot | 2016 |
| ALU TEC Marine Ltd. | Glasgow | 2002 |
| ALU Transport Logistics Limited | Boston | 2020 |
| ALU+ Limited | Kenilworth | 2005 |
| ALU+ Powder Coating Limited | Kenilworth | 2008 |
| Alu-Fast Limited | Halifax | 2024 |
| Alu-Fix (UK) Holdings Limited | Belfast | 2013 |
| Alu-Fix Limited | Middlesbrough | 2004 |
| Alu-Tec (UK) Ltd | Leigh-On-Sea | 2012 |
| Alu/Uk Limited | Waltham Abbey | 2022 |
| Alubau Limited | Oxfordshire | 2014 |
| Alubend Limited | Telford | 2019 |
| Alubend UK Limited | Telford | 2021 |
| Aluca UK Ltd. | Solihull | 2025 |
| Alucard Publishing Limited | West Midlands | 1975 |
| Alucast Group Limited | Wednesbury | 1994 |
| Alucast Limited | West Midlands | 2003 |
| Aluclad Systems Ltd. | London | 2018 |
| Aluco Aluminium Limited | Huntingdon | 2017 |
| Aluco Health Ltd | Diss | 2024 |
| Alucor Limited | Doncaster | 2021 |
| Aludio Limited | London | 2016 |
| Aludoor Ltd | Wirral | 2006 |
| Alufab Engineering Ltd | Belfast | 2024 |
| Alufab Products Ltd | Downpatrick | 2020 |
| Alufab Windows Ltd | London | 2023 |
| Alufar UK Limited | London | 2025 |
| Alufast National Limited | Leeds | 2026 |
| Aluflex Ltd | Leicester | 2023 |
| Alufold Direct Limited | Leeds | 2012 |
| Alufold Window Systems Ltd | Leicester | 2005 |
| Aluform (UK) Ltd | Hull | 2006 |
| Aluframes Direct Ltd | Enfield | 2019 |
| Alufront UK Ltd | Heywood | 2026 |
| Alufusion Systems Limited | Chesterfield | 2025 |