| Birchgree Limited | London | 1981 |
| Birchill Music (Holdings) Limited | Watford | 2024 |
| Birchill Music Projects (Holdings) Limited | Watford | 2024 |
| Birchin Insurance Brokers Ltd | London | 2022 |
| Birchleaf Limited | London | 2005 |
| Birchmoor Holdings Limited | Harrogate | 2025 |
| Birchmount Solutions Ltd | Lincoln | 2017 |
| Bircholt Holdings Limited | London | 2024 |
| Birchpool Limited | Bournemouth | 2025 |
| Birchstone Capital Ltd | London | 2025 |
| Birchstone Care Homes Ltd | Watford | 2022 |
| Birchstone Markets Limited | London | 2021 |
| Birchtree Mortgages Ltd | Widnes | 2024 |
| Birchwood Bidco Limited | London | 2021 |
| Birchwood Capital Limited | Braintree | 2015 |
| Birchwood Care Group Limited | London | 2017 |
| Birchwood Education Holdings Limited | Blackburn | 2025 |
| Birchwood Holdings Ltd | Dromore | 2019 |
| Birchwood Investment Management Limited | Fareham | 1984 |
| Birchwood Mortgages Limited | Warrington | 2011 |
| Birchwood Omnia Limited | Maidenhead | 2000 |
| Birchwood Real Estate Capital UK Limited | London | 2022 |
| Birchwood Topco Limited | London | 2021 |
| Birchwood Wealth Limited | Glasgow | 2021 |
| Birchy Holdings Limited | Hyde | 2022 |
| Birco Group Ltd | Nottingham | 2026 |
| Bircroft Insurance Services Limited | London | 1991 |
| Bircroft Private (Scot) Ltd | Glasgow | 2024 |
| Bircroft Private Ltd | Weybridge | 2009 |
| Bird & Co Mortgage and Financial Solutions Limited | London | 2015 |
| Bird Bidco Limited | Altrincham | 2024 |
| Bird Box Bonds PLC | Chorley | 2018 |
| Bird Family Investments Limited | Solihull | 2020 |
| Bird Finance Ltd | London | 2025 |
| Bird Group Holdings Limited | East Tilbury | 2023 |
| Bird Group Limited | Coventry | 2024 |
| Bird Hospitality Limited | London | 2012 |
| Bird Stewart Financial Services Limited | Airdrie | 2012 |
| Bird Street Enterprises Limited | Scarborough | 2016 |
| Bird Trustee Company | London | 1975 |
| Birdi Holdco Limited | Romford | 2024 |
| Birdie Holdco Limited | London | 2023 |
| Birdie Investments Limited | Bolton | 2023 |
| Birdie Nominee Limited | Driffield | 2023 |
| Birdland Limited | London | 2022 |
| Birdland Park Holdings Limited | Sherborne | 2023 |
| Birds (Derby) Pension Trustee Limited | Derby | 2020 |
| Birds of Paradise Limited | London | 2025 |
| Birds Online Limited | Stafford | 2022 |
| Birdsall Inns Holdings Limited | Sidcup | 2014 |
| Birdshill 54 Limited | London | 2021 |
| Birdsong Holdings Limited | London | 2023 |
| Birdstrike Management Holdings Limited | York | 2025 |
| Birdtop Limited | Nottingham | 2020 |
| Birdview Investments Limited | Ilford | 2026 |
| Birgan Holdings Limited | Redditch | 2022 |
| Birgham Bidco Limited | Cardiff | 2026 |
| Birgham Midco 1 Limited | Cardiff | 2026 |
| Birgham Midco 2 Limited | Cardiff | 2026 |
| Birgham Topco Limited | Cardiff | 2026 |
| Birk Holdings Limited | Sheffield | 2017 |
| Birkdale Broking Group Limited | Southport | 2020 |
| Birkdale Financial Planning Limited | Southport | 2024 |
| Birkdale Park Land Company Limited | Wirral | 1874 |
| Birkdale Wealth Management Ltd | Burscough | 2015 |
| Birkett & Birkett Limited | Nottingham | 2021 |
| Birkett Chambers Limited | Orkney | 2022 |
| Birkett Financial Planning Limited | Wigan | 2022 |
| Birks Holdings Ltd | Chesterfield | 2022 |
| Birley & Jakeman Holdings Limited | Coventry | 2019 |
| Birley Pastry Holdings Limited | London | 2023 |
| Birlic Holdings Ltd | Birmingham | 2022 |
| Birlik Investment Ltd | London | 2015 |
| Birling Group Limited | Cheshunt | 1986 |
| Birmingham Airport (Finance) PLC | Birmingham | 2000 |
| Birmingham Airport Pension Trustees Limited | Birmingham | 2013 |
| Birmingham Bank Limited | London | 1955 |
| Birmingham Campus Property Limited | London | 2024 |
| Birmingham City Mortgages Ltd | Birmingham | 2017 |
| Birmingham City Stadium Ltd | Birmingham | 2019 |
| Birmingham Educational Investments Limited | Newcastle Upon Tyne | 2021 |
| Birmingham Endeavour Limited | Birmingham | 2016 |
| Birmingham Glass Group Limited | Birmingham | 2024 |
| Birmingham Glass Holdings Limited | Birmingham | 2018 |
| Birmingham Group Ltd | Birmingham | 2023 |
| Birmingham Highways Holdings Limited | Birmingham | 2009 |
| Birmingham Holdings Limited | Coleshill | 2016 |
| Birmingham Investment Group Ltd | Birmingham | 2019 |
| Birmingham Mortgage Hub Limited | Birmingham | 2025 |
| Birmingham MOT Holdings Limited | Birmingham | 2025 |
| Birmingham Opco Limited | London | 2021 |
| Birmingham Plating Holdings Limited | Warley | 2024 |
| Birmingham Propco Limited | London | 2021 |
| Birmingham Schools Partnership (Group) Limited | Swanley | 2003 |
| Birmingham Schools Partnership (Holdings) Limited | Swanley | 1999 |
| Birmore Limited | London | 2013 |
| Birnam Motor Salvage (Holdings) Ltd | Glasgow | 2019 |
| Birnbeck Finance Limited | Weston Super Mare | 1974 |
| Birnie Holdings Ltd | Dumbarton | 2026 |
| Biro Fleabag Ltd | Swanley | 2021 |