| Buster Jimmy Private Equity Limited | Derby | 2022 |
| Buster Jimmy S4S Limited | Derby | 2022 |
| Bustler Holdings Ltd | Derby | 2026 |
| Busy BEE Cleaning Holdings Limited | Bath | 2026 |
| Busy BEE Commercial Finance Limited | Manchester | 2020 |
| Busy BEE Mortgage and Protection Solutions Limited | Southampton | 2021 |
| Busy Box Limited | Derby | 2014 |
| Busy Investments Limited | Warrington | 2024 |
| Busybee Finance Ltd | Otley | 2011 |
| Busylindsay Limited | Barnet | 2019 |
| Busysky Holdings Limited | Sheffield | 2022 |
| Buta Topco Limited | Leeds | 2019 |
| Butch's Park Holdings Limited | Weymouth | 2021 |
| Butcher & Moody Financial Services Limited | Chandlers Ford | 2018 |
| Butcher Group Holdings Limited | Doncaster | 2025 |
| Butcher Holdings Ltd | Ipswich | 2023 |
| Butcher Robinson & Staples Holdings Limited | London | 2001 |
| Butcher Robinson & Staples Marine Limited | London | 1989 |
| Butcher, Robinson & Staples International Limited | London | 1962 |
| Butcher, Robinson & Staples Limited | London | 1976 |
| Bute Energy Development Holdings Limited | Cardiff | 2021 |
| Bute Financial Limited | London | 2024 |
| Bute Rock Limited | Reigate | 2021 |
| Bute ST Investments Limited | Treorchy | 2022 |
| Butler & Britannia Holdings Ltd | London | 2023 |
| Butler & Butler (Holdings) Ltd | Torquay | 2011 |
| Butler & Butler Group Ltd | Waterlooville | 2018 |
| Butler Corporation Limited | Evesham | 2020 |
| Butler Family Investments Limited | London | 2018 |
| Butler Financial Services Limited | Newcastle Upon Tyne | 2012 |
| Butler Financial Solutions Ltd | Andover | 2026 |
| Butler Group Holdings Limited | Derby | 2025 |
| Butler Holdings Yorkshire Limited | Aldbrough | 2025 |
| Butler House (North East) Ltd | Darlington | 2020 |
| Butler Investment Managers Limited | London | 2007 |
| Butler Management Holding Limited | London | 2017 |
| Butler Management Limited | London | 2009 |
| Butler Mortgage Solutions Ltd | Ballycastle | 2021 |
| Butler Mortgages Limited | Trowbridge | 2003 |
| Butler Recruitment Limited | Derby | 2019 |
| Butler Stream Limited | Belfast | 2022 |
| Butler Street Venture Capital Group Ltd | London | 2024 |
| Butler Symonds Ltd | Peterborough | 2012 |
| Butler Technik Group Ltd | Lincoln | 2024 |
| Butler Toll Limited | Swindon | 2005 |
| Butler Toll Services Limited | London | 2002 |
| Butlers Coffee Holdings Ltd | Nottingham | 2024 |
| Butlers Holdings Ltd | Farnborough | 2024 |
| Butlers Mortgages Limited | Romsey | 2024 |
| Butlers Waste Management Holdings Limited | Newcastle Under Lyme | 2019 |
| Butt & Hobbs Holdings Limited | Dewsbury | 2026 |
| Butt & Oyster Limited | Market Harborough | 2022 |
| Butter Holdings Ltd | London | 2019 |
| Butter SPV 1 Ltd | London | 2020 |
| Buttercross Financial Limited | Doncaster | 2015 |
| Buttercup Environmental Ltd | Bexhill-On-Sea | 2025 |
| Buttercup Investment Holdings Limited | Glasgow | 2023 |
| Buttercups Group Limited | Nottingham | 2018 |
| Buttercups Holdings Limited | Nottingham | 2023 |
| Butterfield Mortgages Limited | London | 1938 |
| Butterfly (Finance) Limited | Carlisle | 2017 |
| Butterfly Bidco Limited | London | 2021 |
| Butterfly Financial Services Limited | Coventry | 2015 |
| Butterfly Group Enterprises Limited | Waterlooville | 2023 |
| Butterfly Group Holdings Limited | Nottingham | 2023 |
| Butterfly London Group Limited | Stowmarket | 2016 |
| Butterfly Midco Limited | London | 2021 |
| Butterfly Topco Limited | London | 2021 |
| Butterflyesg Ltd | London | 2021 |
| Butterfox Holdings Ltd | Manchester | 2026 |
| Butterley Investco Limited | Wakefield | 2024 |
| Buttermere Capital Limited | Hove | 2018 |
| Buttermilk Holdings Limited | Bodmin | 2025 |
| Butterstone Holdings Ltd | Chelmsford | 2024 |
| Butterworth Estate Solutions Ltd | Hockley | 2025 |
| Butterworth Investments Limited | Birmingham | 1928 |
| Butterworth Marine Holdings Limited | Scarborough | 2021 |
| Butterworth Spengler (Cyclesure) Limited | Leeds | 1981 |
| Butterworth Spengler Commercial Limited | Leeds | 2004 |
| Butterworth Spengler Group Limited | Leeds | 2020 |
| Butterworth Spengler Professional Risks Limited | Leeds | 2009 |
| Butterworth Spengler South West Limited | Leeds | 1997 |
| Buttinghill Investments Limited | Norwich | 2019 |
| Button Enterprise Limited | Penrith | 2021 |
| Button Holdings Limited | Hertfordshire | 1992 |
| Button Investments Limited | Cambridge | 2026 |
| Button MGA Limited | London | 2025 |
| Button Property Developments Limited | Cambridge | 2026 |
| Button Property UK Limited | London | 2015 |
| Buttonfix Holdings Ltd | London | 2018 |
| Buttons Financing Ltd | Colchester | 2021 |
| Buttons Investments Ltd | London | 2026 |
| Buttr Financial Services UK Limited | London | 2025 |
| Buttr Group Limited | London | 2025 |
| Buttress Holdings Limited | Brackley | 2020 |
| Butyl Tapes Holdings Ltd | Liverpool | 2022 |
| Buuk Infrastructure Limited | Bury St. Edmunds | 2005 |
| BUX & Co. Limited | Preston | 2012 |
| BUX Holdings Ltd | Darwen | 2021 |
| BUX Investments Ltd | Leicester | 2017 |