| 56 Degrees (Holdings) Ltd | Wilmslow | 2025 |
| 56 Global Ltd | London | 2026 |
| 56 Godolphin Road Management Limited | London | 2023 |
| 56 Holdings Group Ltd | Bradford-On-Avon | 2026 |
| 56 Regents Park Road Managements Limited | | 1978 |
| 56 Windmills Ltd | Salisbury | 2024 |
| 5622 Holdings Limited | Edinburgh | 2022 |
| 5678 Limited | London | 2020 |
| 57 Capital Limited | Burnley | 2018 |
| 57 Commercial Finance Limited | Southampton | 2020 |
| 57 North Financial Planning Ltd | Braintree | 2022 |
| 57 Sheen Lane Management Company Limited | London | 2018 |
| 575 LEV Investments Limited | Bolton | 2020 |
| 57AG Limited | Ealing | 2022 |
| 57N Mortgages Ltd | Aberdeen | 2025 |
| 58E Advice Limited | Bathgate | 2018 |
| 59 Group Ltd | London | 2022 |
| 59 Investments Limited | Manchester | 2024 |
| 591 Automotive Group Limited | Alton | 2024 |
| 5AB Holdings Limited | Letchworth Garden City | 2022 |
| 5C Holdings Limited | Solihull, West Midlands | 2022 |
| 5D Capital Holdings Ltd | Sale | 2026 |
| 5D Finance Limited | Chatham | 2006 |
| 5D Ventures Ltd | London | 2022 |
| 5DC Green Limited | London | 2026 |
| 5DT (Holdings) Limited | Bilston | 2024 |
| 5EATS04 Ltd | Tunbridge Wells | 2026 |
| 5F Holdings Ltd | Birmingham | 2021 |
| 5G Asset Management Limited | Sheffield | 2017 |
| 5HELIX Ltd | London | 2025 |
| 5HS Holdings Ltd | Rochester | 2026 |
| 5IVE Ventures Ltd | Bolton | 2021 |
| 5K Capital Holdings Ltd | London | 2025 |
| 5K Homes Holdings Ltd | Birmingham | 2022 |
| 5M Holdings Ltd | Renfrew | 2021 |
| 5NM Ltd | Glasgow | 2022 |
| 5PLUS INT. Trading Ltd | Wrexham | 2016 |
| 5PR TW Holdings Limited | London | 2025 |
| 5R1 Limited | Harrow | 2007 |
| 5RACKS Holdings Ltd | Welling | 2025 |
| 5RB Ltd | East Ham | 2015 |
| 5S Capital Ltd | London | 2026 |
| 5S Global Investments Limited | Coventry | 2025 |
| 5S Holdings Limited | Coventry | 2025 |
| 5S Mortgage Solutions Limited | Leicester | 2023 |
| 5SQUARE Global Limited | Leicester | 2022 |
| 5TEC Ltd | Andover | 2023 |
| 5TH Stage Limited | London | 2020 |
| 5TH Venture Labs Ltd | London | 2026 |
| 5TH Wheel Accident Claims Limited | Irvine | 2019 |
| 5TO-GO Limited | London | 2025 |
| 5X Ltd | Cardiff | 2021 |
| 5X Ventures Holding Limited | Walton-On-Thames | 2026 |
| 5XFIVE Ltd | London | 2023 |
| 5XM Finance and Consulting Ltd | Upminster | 2016 |
| 6 Alpha Associates Limited | Rickmansworth | 2004 |
| 6 Blyth Road Management Company Limited | Bromley | 2016 |
| 6 Energy Services Limited | Fraserburgh | 2008 |
| 6&4 Limited | London | 2023 |
| 6'ERS Group Limited | Portsmouth | 2015 |
| 60 TLI Holdings Limited | Lincoln | 2024 |
| 6000 GM Limited | Upminster | 2014 |
| 601 Financial Solutions Limited | Basildon | 2005 |
| 606 Square | London | 2016 |
| 6087 Holdings Limited | Stockport | 2025 |
| 611 Investments Ltd | Cheltenham | 2021 |
| 615 Walnut Tree Limited | Cambridge | 2023 |
| 617 Holdings Limited | London | 2021 |
| 61M Ltd | London | 2014 |
| 62 Dean Street Soho London Limited | London | 2014 |
| 62 DRY Hill Park Road Tonbridge Limited | London | 2017 |
| 62 Investments Ltd | Dewsbury | 2024 |
| 63 Mark Lane Limited | London | 2026 |
| 64 Capital Limited | Lytham St. Annes | 2026 |
| 64 Delta Invest Ltd | London | 2022 |
| 64QS Holdings Limited | Edinburgh | 2021 |
| 64TEQ Holdings Limited | Warrington | 2021 |
| 65 Castletown Road Management Company Limited | Glasgow | 2010 |
| 65 Health & Aesthetics Group Ltd | Brentwood | 2026 |
| 65 Sports Holdings Limited | Borehamwood | 2025 |
| 65TS Holdings Limited | London | 2022 |
| 66 Capital Ltd | Watford | 2020 |
| 666 Leisure Holdings Limited | Beverley | 2024 |
| 666 Lilith Limited | Beverley | 2024 |
| 666 LOW Holdings Limited | Beverley | 2019 |
| 666 Richmond Group Limited | Beverley | 2024 |
| 6706 Limited | Oldham | 2019 |
| 68-33 Company Limited | London | 2023 |
| 683 Ltd | Bishop'S Stortford | 2022 |
| 69 Freegrove Road Limited | London | 2010 |
| 69-71 Staines Road East (Freehold) Ltd | Ashford | 2021 |
| 6AP Family Investments Limited | Ilford | 2023 |
| 6B Group Ltd | Wokingham | 2022 |
| 6B Holdings Limited | Lincoln | 2021 |
| 6B Ventures Ltd | Wakefield | 2024 |
| 6CATS UK Services Ltd | Watford | 2018 |
| 6CU Holdings Ltd | Oldham | 2023 |
| 6CVENTURES Ltd | Cardiff | 2020 |
| 6DG Holdco Limited | London | 2022 |
| 6DG Topco Limited | London | 2022 |