| Allen IP Limited | Birmingham | 2008 |
| Allen James Limited | London | 2023 |
| Allen Legal Services Limited | York | 2024 |
| Allen Leslie Associates Limited | Colchester | 2005 |
| Allen Management Services Ltd | Brenchley | 2025 |
| Allen Mcdougall Mangement Consultants Ltd | Wolverhampton | 2016 |
| Allen Mills Howard Limited | Altrincham | 2002 |
| Allen Moss Ltd. | Haywards Heath | 2017 |
| Allen Organs (NI) Ltd | Dromore | 2004 |
| Allen Overy Shearman Sterling (Holdings) Limited | London | 2010 |
| Allen Overy Shearman Sterling (KSA Holdings) Limited | London | 2023 |
| Allen Overy Shearman Sterling (Legal Advisers) Limited | London | 1992 |
| Allen Overy Shearman Sterling (Trustee) Limited | London | 2016 |
| Allen Overy Shearman Sterling Pension Trustee Limited | London | 1977 |
| Allen Overy Shearman Sterling Service Company Limited | London | 1987 |
| Allen Packaging Consultancy Limited | Ruislip, | 2025 |
| Allen People Solutions Ltd | Belfast | 2007 |
| Allen PI Ltd | Lytham St.Annes | 2024 |
| Allen Planning Ltd | Salisbury | 2011 |
| Allen Process Solutions Ltd | London | 2019 |
| Allen Project Consulting Limited | Bristol | 2019 |
| Allen Quality Management Ltd | Buckley | 2023 |
| Allen Robyn & Associates Limited | London | 1999 |
| Allen Rose Associates Limited | Stafford | 2012 |
| Allen Safety and Training Limited | Liverpool | 2014 |
| Allen Scobie Consultancy Limited | Perth | 2021 |
| Allen Scott Limited | Tunbridge Wells | 2005 |
| Allen Strategic Advisory Ltd | Elgin | 2026 |
| Allen Studios Ltd | Pulborough | 2024 |
| Allen Sykes Audit Limited | Bishop Auckland | 2025 |
| Allen Sykes Limited | Bishop Auckland | 1988 |
| Allen Taylor Consulting Ltd | London | 2016 |
| Allen Taylor Management Ltd | London | 2023 |
| Allen Thiang Ltd | London | 2012 |
| Allen TTC Ltd | Billericay | 2013 |
| Allen VA Limited | Luton | 2023 |
| Allen Ventures Services UK Ltd | Chipping Norton | 2020 |
| Allen, Everest and Associates Limited | Wellingborough | 2015 |
| Allen, West and Foster Limited | Sheffield | 2017 |
| Allen-Aldus Surveying Ltd | Norwich | 2024 |
| Allen-Mullen PUB Co. Limited | Bury | 2017 |
| Allen-Vanguard Ltd | London | 1975 |
| Allen.O Limited | London | 2017 |
| Allenbuild (South East) Ltd | London | 1981 |
| Allenby Accountants Ltd | Uxbridge | 2010 |
| Allenby Design Ltd | York | 2020 |
| Allenby Engineering Limited | Hull | 2025 |
| Allenby Marketing Limited | Cambridge | 2020 |
| Allencrest Limited | Southampton | 1991 |
| Allendale Associates Ltd | Hereford | 2017 |
| Allendale Management Limited | Hexham | 2004 |
| Allendale Trustees 1 Limited | Stocksfield | 2022 |
| Allendale Trustees 2 Limited | Stocksfield | 2022 |
| Allendene Limited | Chichester | 2008 |
| Alleneagle Limited | Haywards Heath | 2007 |
| Allenergy Consult Ltd | Edinburgh | 2026 |
| Allenfd Limited | London | 2012 |
| Allenfield Ltd | Cheltenham | 2025 |
| Alleng Solutions Ltd | Dromore | 2015 |
| Allengaged Ltd | Newcastle Upon Tyne | 2022 |
| Allenhayes Technical Services Limited | Stoughton | 2022 |
| Allenheads Trust Limited | Hexham | 2002 |
| Allenhurst Solutions Limited | Knaresborough | 2011 |
| Allenko Limited | London Docklands | 2012 |
| Allenlytic Ltd | Cottingham | 2025 |
| Allenpharma Limited | London | 2006 |
| Allens Accountants Ltd. | Cheshire | 2002 |
| Allens Cadge & Gilbert Ltd | Bungay | 2016 |
| Allens Creek Advisory Ltd | London | 2026 |
| Allens' Tax Disputes Limited | Warrington | 2022 |
| Allenshaw Services Ltd | London | 2019 |
| Allentay Limited | Kettering | 2018 |
| Allentra Ltd | Yeovil | 2025 |
| Aller Brook Ltd | Hemel Hempstead | 2010 |
| Aller Engineering (South West) Limited | Ilminster | 2015 |
| Allera Marketing Ltd | Broxburn | 2022 |
| Allerayde SAB Limited | Newark | 2012 |
| Allerbeste International UK Ltd | Manchester | 2023 |
| Allerbray Limited | Birmingham | 2018 |
| Allerdice Project Management Limited | Hamilton | 2025 |
| Allerford Consulting Limited | Taunton | 2019 |
| Allergan Holdco UK Limited | Marlow | 2016 |
| Allergan Holdings Limited | Marlow | 1988 |
| Allergies Indoors and OUT Ltd | Malvern | 2010 |
| Allergy Consulting Ltd | Leamington Spa | 2024 |
| Allergy Research Limited | Dartford | 1998 |
| Allergy Technologies Ltd | London | 2025 |
| Allergy Therapeutics (Holdings) Limited | West Sussex | 1998 |
| Allergydoctor UK Limited | Manchester | 2014 |
| Alleria Media Ltd | London | 2026 |
| Allermuir Capital Limited | London | 2021 |
| Allermuir Consultancy Services Ltd | Edinburgh | 2024 |
| Allermuir Laverock Limited | Edinburgh | 2011 |
| Allershaw Limited | Blackwood | 2008 |
| Allerspot Ltd | Ruislip, | 2024 |
| Allerton & Gladstone Ltd | Birmingham | 2020 |
| Allerton Associates Ltd | Bridgwater | 2011 |
| Allerton Communications Limited | Guildford | 2008 |
| Allerton Design Limited | Liverpool | 2020 |
| Allerton Group Limited | Watford | 2018 |