| 55 Digital Ltd | Worcester | 2021 |
| 55 Group Ltd | Bristol | 2024 |
| 55 Hackford Road Limited | London | 2009 |
| 55 Holdings Limited | London | 2020 |
| 55 Leeds Ltd | Leeds | 2020 |
| 55 Live Ltd | London | 2020 |
| 55 North Network Limited | Thurso | 2008 |
| 55 Solutions Limited | Wokingham | 2012 |
| 55 South Norwood Hill Residents Company Limited | South Norwood | 1992 |
| 55 Stapleton Hall Road Residents Association Limited | | 1987 |
| 55 Studio Limited | Basingstoke | 2026 |
| 55 Valetta Road Limited | London | 1991 |
| 55-64 West Kensington Mansions Management Co. Limited | London | 1993 |
| 550 Energy Limited | Wymondham | 2020 |
| 5501VM Ltd | Norwich | 2018 |
| 551 Consulting Limited | Warrington | 2015 |
| 551 High RD Ltd | Salford | 2022 |
| 5538 Management Limited | Torquay | 2020 |
| 555 Technologies Limited | Slough | 2021 |
| 55555 Ltd | Blackpool | 2025 |
| 556 Safety Limited | Tonypandy | 2024 |
| 557 Taxis Ltd. | Edinburgh | 2007 |
| 558 Edin Ltd. | Glasgow | 2005 |
| 558 Services Limited | Blackpool | 2021 |
| 55E Consulting Limited | London | 2024 |
| 55E5 Ltd | London | 2014 |
| 55GMA Fitting Ltd | Hemel Hempstead | 2023 |
| 55N Consulting Limited | Holywood | 2013 |
| 55NORTH Digital Ltd | Weybridge | 2015 |
| 55P Ltd | King'S Lynn | 2020 |
| 55TH Parallel Ltd. | Newcastle Upon Tyne | 2017 |
| 55ZERO Labs Ltd | St. Albans | 2018 |
| 56 Consultancy Ltd | Leicester | 2023 |
| 56 Degree Insight Ltd | Dalkeith | 2019 |
| 56 Degrees North Ltd | Edinburgh | 2020 |
| 56 Developments EA Ltd | Norwich | 2017 |
| 56 Lane Ltd | London | 2021 |
| 56 Marlborough Road Freehold Limited | London | 2004 |
| 56 North Consulting Ltd | Avoch | 2021 |
| 56 Stuart Road Management Company Limited | Plymouth | 1998 |
| 56 Vincent Square Limited | London | 2006 |
| 56 Wealth Management Limited | Edinburgh | 2020 |
| 56-58 North Street Freehold Limited | Bristol | 2013 |
| 56.56 North Ltd | Pewsey | 2023 |
| 561 Edin Ltd. | Newbridge | 2004 |
| 5654 & Company Limited | London | 2020 |
| 568 Consulting Ltd | London | 2023 |
| 568 Edin Ltd. | Edinburgh | 2006 |
| 56A Consulting Ltd | Larbert | 2020 |
| 56CW Services Limited | London | 2022 |
| 56THREE Architects Ltd | Edinburgh | 2005 |
| 56THREE Group Ltd | Edinburgh | 2018 |
| 57 Advisory Ltd | High Wycombe | 2025 |
| 57 Agency Ltd | London | 2022 |
| 57 and 59 Kitchener Road Limited | | 2005 |
| 57 Anson Road Limited | London | 1985 |
| 57 Clarendon Nominees (NO. 2) Limited | Cheltenham | 2023 |
| 57 Clarendon Nominees Limited | Cheltenham | 2022 |
| 57 Dukes Avenue Limited | London | 2021 |
| 57 Fresh Ventures Group Ltd | Uxbridge | 2025 |
| 57 Godstone Road Management Company Limited | Surrey | 1991 |
| 57 Idmiston Ltd | London | 2013 |
| 57 Jevington Gardens (Eastbourne) Limited | London | 2007 |
| 57 Media Ltd | Doncaster | 2020 |
| 57 North Consultants Ltd | Aberdeen | 2026 |
| 57 North Ltd | Aberdeen | 2026 |
| 57 Stacey Road Management Company Limited | Cardiff | 2003 |
| 570 Mediaphotography Limited | W Yorkshire | 2006 |
| 571 Consultants Ltd | Datchet | 2016 |
| 571 Music Consulting and Solutions Ltd | Rochester | 2024 |
| 573 Taxis Ltd | Edinburgh | 2014 |
| 578 Hayes Ltd | London | 2015 |
| 578 Taxis Ltd | Edinburgh | 2016 |
| 57MG Limited | Northampton | 2017 |
| 57PHR Art Ltd | London | 2026 |
| 58 Advisory Ltd | Bristol | 2016 |
| 58 Broughton Road Management Company Limited | London | 2000 |
| 58 Browning Road (Worthing) Limited | London | 2001 |
| 58 Coolhurst Road Management Company Limited | London | 2013 |
| 58 Creative Ltd | Birmingham | 2024 |
| 58 Group Ltd | Blandford Forum | 2024 |
| 58 Howitt Road Limited | | 1998 |
| 58 Plimsoll Road Limited | Great Dunmow | 1997 |
| 58 ST Johns Park Management Limited | London | 1998 |
| 58 Theobalds Road Limited | London | 2005 |
| 58 Washway Road Limited | Warwick | 2012 |
| 58 West Cromwell Road Limited | London | 1990 |
| 58 Westbrook Avenue RTM Company Limited | Margate | 2014 |
| 58-60 Crediton Hill Limited | London | 2005 |
| 58/64 Selkirk Road Management Company Limited | Twickenham | 2005 |
| 581 Taxis Limited | Livingston | 2011 |
| 583 Edin Ltd. | Edinburgh | 2003 |
| 585 Consulting Ltd | Reading | 2023 |
| 5858 Engineering Ltd | Liverpool | 2020 |
| 586 Engineering Ltd | Syresham | 2006 |
| 586 Enterprise Limited | Brackley | 2008 |
| 586 Group Limited | Brackley | 2008 |
| 586 Technology Limited | Brackley | 2008 |
| 5865 Limited | Great Dunmow | 2023 |
| 587 Communications Ltd | London | 2024 |