| Alston Hill Ltd. | Nelson | 2008 |
| Alston Investments Holdings Limited | Chorley | 2021 |
| Alston Lodge Group Limited | Longridge | 2017 |
| Alston Ltd | Dorchester | 2021 |
| Alsure Holdings Limited | Birmingham | 2024 |
| ALT 21 Limited | London | 2017 |
| ALT Asset Finance Limited | Buckingham | 2002 |
| ALT Berg Group Limited | Richmond | 2021 |
| ALT Berg Holdings Limited | Richmond | 2012 |
| ALT Finance Ltd | Gerrards Cross | 2013 |
| ALT Group Holdings Limited | Wetherby | 2016 |
| ALT Group UK Holdings Limited | Worcester | 2022 |
| ALT Hill Payments Ltd | Oldham | 2026 |
| ALT Investment Limited | Southampton | 2014 |
| ALT Legal IP Limited | Altrincham | 2026 |
| ALT Prime Global Ltd | London | 2025 |
| Alta Advisers Limited | London | 1996 |
| Alta Asset Management Limited | Berwick Upon Tweed | 2019 |
| Alta Group Holdings Ltd | London | 2025 |
| Alta Signa Holdings Limited | London | 2019 |
| Alta Signa Ltd | London | 2018 |
| Alta Terra Limited | Leominster | 2013 |
| Altaclara Developments Limited | West Horsley | 2017 |
| Altadis Newco Limited | Bristol | 2019 |
| Altadomus Holding Ltd | London | 2025 |
| Altaera Holdings Ltd | Wellingborough | 2026 |
| Altai Resources Limited | London | 2022 |
| Altaif Money Transfer Limited | Greenford | 2014 |
| Altair Credit Limited | London | 2025 |
| Altair FIN Ltd | Preston | 2024 |
| Altair Financial Planning Ltd | London | 2017 |
| Altair Group Holdings Ltd | Tamworth | 2025 |
| Altair Holdings Limited | London | 2023 |
| Altair Renewable Energy Limited | London | 2017 |
| Altalto Immingham Holdings Limited | Oxford | 2018 |
| Altalto Limited | Oxford | 2018 |
| Altamar CAM Partners UK Ltd | London | 2022 |
| Altamira Limited | London | 2025 |
| Altanex Holdings Limited | Birmingham | 2025 |
| Altano UK Limited | Newmarket | 2024 |
| Altanova Holdings Limited | Rickmansworth | 2025 |
| Altaphoria Group Limited | Windsor | 2024 |
| Altara Funding Limited | London | 2025 |
| Altaris Group Limited | Warrington | 2026 |
| Altaris Ventures Ltd | London | 2026 |
| Altarius Global Capital Ltd. | London | 2026 |
| Altarvest Limited | Swansea | 2009 |
| Altasia (Management) Limited | London | 2023 |
| Altasia Limited | London | 2023 |
| Altavelta Ltd | London | 2026 |
| Altaventure Limited | London | 2026 |
| Altavere Holdings Ltd | London | 2026 |
| Altawakul Properties Ltd | Liverpool | 2024 |
| Altcar Property Holdings Limited | Preston | 2020 |
| Altco Holdings Limited | London | 2012 |
| Altcoin Trades Ltd | Luton | 2014 |
| Altctrl Holdings Limited | Totnes | 2026 |
| Altdigitize UK Limited | London | 2025 |
| Alte Investment Limited | London | 2019 |
| Altea UK Group Limited | London | 2025 |
| Altec Products Limited | St. Austell | 1987 |
| Alteco Investments Limited | London | 2023 |
| Altekgo Limited | Alton | 2023 |
| Altenergy Group Limited | Taunton | 2023 |
| Altens Development Company Limited | Aberdeen | 2015 |
| Altent Holdings Limited | London | 2022 |
| Alter Domus (UK) Limited | London | 2011 |
| Alter Domus Agency Services (UK) Limited | London | 2014 |
| Alter Domus DCM (UK) Limited | London | 2014 |
| Alter Domus Depositary Services (UK) Limited | London | 2013 |
| Alter Domus Financial Services (UK) Limited | London | 2014 |
| Alter Domus Fund Services (UK) Limited | London | 2014 |
| Alter Domus Trustees (UK) Limited | London | 2014 |
| Alter Plano Limited | Edinburgh | 2014 |
| Alter Technology TUV Nord Holdings Limited | Livingston | 2008 |
| Alter-Native Solutions UK Ltd | Leyton | 2009 |
| Altera Infrastructure Arendal Holdings Limited | Westhill | 2022 |
| Altera Infrastructure Ffta Holdings Limited | Westhill | 2022 |
| Altera Infrastructure Fpso Holdings Limited | Westhill | 2022 |
| Altera Infrastructure FSO Holdings Limited | Westhill | 2020 |
| Altera Infrastructure Production Holdings Limited | Westhill | 2020 |
| Altera Infrastructure Voyageur Holdings Limited | Westhill | 2023 |
| Altera Partners Management Limited | London | 2003 |
| Alterares Holdings Ltd | Derby | 2022 |
| Alteri ERS Co-Investments Limited | London | 2023 |
| Alterion Ltd | London | 2000 |
| Alteris 2 Limited | London | 2017 |
| Alteris Partners Limited | London | 2015 |
| Alterium Limited | Ipswich | 2013 |
| Alternativa Ltd | Croydon | 2014 |
| Alternative Assets Ltd | Greenock | 2026 |
| Alternative Bridging (Management) Limited | Borehamwood | 2019 |
| Alternative Bridging (UK 1) Limited | Borehamwood | 2014 |
| Alternative Bridging (UK 2) Limited | Borehamwood | 2016 |
| Alternative Bridging (UK3) Limited | London | 2024 |
| Alternative Bridging Corporation (Cheval) Limited | Borehamwood | 2001 |
| Alternative Bridging Corporation Limited | Borehamwood | 2010 |
| Alternative Commercial Finance Limited | Lincoln | 2013 |
| Alternative Commercial Mortgages Limited | Borehamwood | 2026 |
| Alternative Credit Investments Limited | London | 2013 |