| 65 ST Paul's Avenue Limited | | 2005 |
| 65 the Chase Limited | London | 2011 |
| 650B Limited | Brighton | 2015 |
| 650D Limited | London | 2025 |
| 650NED Ltd | Newport Pagnell | 2023 |
| 651 Consulting Ltd | Leigh-On-Sea | 2021 |
| 652SOUTH Limited | Knowle, Solihull | 2011 |
| 657 Advisory Limited | Eastleigh | 2025 |
| 657 Consulting Ltd | Chester | 2021 |
| 6570 Consulting Limited | Hornchurch | 2024 |
| 65DS Limited | Woodford Green | 2011 |
| 66 BEE Ltd | Glasgow | 2022 |
| 66 Books Trustees Ltd | London | 2025 |
| 66 Consultancy Limited | Winchester | 2022 |
| 66 Design Consultancy Limited | Gloucestershire | 2009 |
| 66 Design Workshop Limited | Benfleet | 2015 |
| 66 Effra Road Freeholders Limited | | 1999 |
| 66 Great North Road Limited | London | 2004 |
| 66 Holding Blue Limited | Twickenham | 2024 |
| 66 Kapkoh Ltd | Poole | 2019 |
| 66 Marketing Solutions Limited | Chester | 2022 |
| 66 Miles Limited | London | 2024 |
| 66 Onslow Gardens Management Company Limited | | 1986 |
| 66 Professional Services Ltd | London | 2002 |
| 66 Reasons Limited | London | 2020 |
| 66 Solutions Ltd | Bromley | 2019 |
| 66-72 Arbour Close Freehold Limited | Rugby | 2007 |
| 66-EWASTE Ltd | Loughborough | 2024 |
| 660 Engineering Ltd | Dorchester | 2025 |
| 662 Sports Media Limited | London | 2024 |
| 662 Ventures Limited | London | 2015 |
| 663 Design Ltd | London | 2021 |
| 6634 Ltd | Kingussie | 2024 |
| 664TECH Ltd | Wellingborough | 2019 |
| 666 Consultants Limited | Preston | 2020 |
| 666 Technologies Ltd | London | 2014 |
| 668 Design & Engineering Ltd | Hatfield | 2018 |
| 66B at Stretton Limited | Warwick | 2025 |
| 66M Ltd | North Berwick | 2024 |
| 66UBS Services Ltd | Northampton | 2018 |
| 67 Artists Ltd | London | 2025 |
| 67 Consulting Limited | Gerrards Cross | 2018 |
| 67 Health Limited | London | 2019 |
| 67 Hedgerows Ltd | Alfreton | 2025 |
| 67 Woodford Road Freehold Limited | London | 2005 |
| 67-73 Park Street Limited | Camberley | 2016 |
| 676 Finchley Road Management Company Limited | London | 1998 |
| 677 Taxis Ltd. | Livingston | 2007 |
| 678 Consult Limited | Erith | 2012 |
| 6791 Engineering Services Limited | Colchester | 2017 |
| 67C Ltd | Redruth | 2023 |
| 68 and 68A Holmesdale Road RTM Company Limited | London | 2016 |
| 68 Auto Performance Limited | Woodbridge | 2011 |
| 68 Balcombe Street Limited | Charlton Musgrove | 2001 |
| 68 Communications Ltd | Preston | 2019 |
| 68 Consulting Limited | Sudbury | 2022 |
| 68 Priory Road Management Company Limited | London | 1993 |
| 68 Seconds Ltd | Wirral | 2020 |
| 68 ST John's Road Limited | Sevenoaks | 2020 |
| 682 Limited | Bridlington | 2024 |
| 683 Edin Ltd. | Glasgow | 2007 |
| 684 Ltd | London | 2024 |
| 68K Cryptocurrency Ltd | Liverpool | 2021 |
| 68K Enterprises Ltd | Liverpool | 2022 |
| 68K Finance Ltd | Liverpool | 2021 |
| 68K Management Ltd | Manchester | 2020 |
| 69 & 69A Northumberland Park (Management) Limited | London | 1997 |
| 69 Appach Road Limited | London | 2002 |
| 69 Babington Road Freehold Company Ltd | Streatham | 2004 |
| 69 Carlyle Road (Freehold) Limited | London | 2008 |
| 69 Chippenham Road Management (1993) Company Limited | London | 1993 |
| 69 Cromwell Street Management Company Limited | | 1989 |
| 69 Limited | Bedford | 2010 |
| 69 Market Street Limited | Bradford | 2014 |
| 69 ST Georges Square Management Limited | Eastbourne | 2003 |
| 69-71 Stoats Nest Road Management Company Limited | Coulsdon | 1990 |
| 69/71 Pont Street Limited | Guildford | 2004 |
| 690 Taxis Ltd. | Prestonpans | 2022 |
| 6912 Limited | Wakefield | 2007 |
| 694 Edin Ltd. | Edinburgh | 2004 |
| 69ENTERTAINMENTBRAND Ltd | Harlow | 2022 |
| 6A Limited | London | 1999 |
| 6AM Collective Ltd | London | 2025 |
| 6AM Group Ltd | London | 2024 |
| 6AP Ltd | Ilford | 2023 |
| 6BASS Ltd | London | 2026 |
| 6BB Ltd | Blackburn | 2022 |
| 6BC Services Ltd | London | 2025 |
| 6BH Consultancy Ltd | Sherborne | 2017 |
| 6C Procurement Limited | St. Columb | 2020 |
| 6CATS Group Ltd | Watford | 2016 |
| 6CATS Pro Ltd | Watford | 2020 |
| 6CC Business Consultants Limited | Gateshead | 2010 |
| 6D Consulting Limited | Bristol | 2003 |
| 6D Digital Limited | Carnforth | 2012 |
| 6D-DEMENTIA Ltd. | Portrush | 2023 |
| 6DEGREES (Sussex) Ltd | Bognor Regis | 2026 |
| 6DEGRESS Ltd | Bognor Regis | 2026 |
| 6DEV Ltd | Southam | 2026 |
| 6DM Ltd | Worcester | 2011 |