| 19EIGHTY Limited | Leamington Spa | 2014 |
| 19GO Business Solutions Limited | Leicester | 2009 |
| 19GR Ltd | Paisley | 2023 |
| 19HD Consultancy Services Limited | Woodford Green | 2020 |
| 19I Ltd | Lightwater | 2019 |
| 19M Ltd | Bury St. Edmunds | 2021 |
| 19NINETYTWO Ltd | Buckhurst Hill | 2025 |
| 19SEVEN Associates Limited | Swanscombe | 2025 |
| 19TH Century Art Limited | London | 1962 |
| 1:9:90 Consulting Limited | London | 2021 |
| 1A Global Control Center Limited | Grangetown | 2009 |
| 1A Smart Solutions Ltd | Sutton | 2021 |
| 1AARCH Limited | Crawley | 2026 |
| 1AESTHETIC Ltd. | Beckenham | 2010 |
| 1AFFORDABLECALL Ltd. | Crawley | 2011 |
| 1AI Ltd | York | 2025 |
| 1AIM Asset Management Limited | Brierley Hill | 2000 |
| 1AIM Digital Ltd | Manchester | 2024 |
| 1AIME Ltd | Romford | 2025 |
| 1B Ltd | London | 2012 |
| 1BBANDB Ltd | Swanage | 2009 |
| 1BD Coaching Limited | London | 2025 |
| 1BDM Limited | Nottingham | 2021 |
| 1BIGRIG Ltd | London | 2021 |
| 1BIM Limited | Keighley | 2021 |
| 1BIZ Ltd | Blackburn | 2023 |
| 1BUILD Commercial Services Limited | Northampton | 2018 |
| 1BUSINESS Consulting Limited | Glasgow | 2017 |
| 1CARE Health Ltd | London | 2024 |
| 1CHANCE Ltd | London | 2026 |
| 1CHILDCONSULTANCY Ltd | London | 2025 |
| 1CLICKSTUDIO Limited | Dagenham | 2017 |
| 1CONWY Ltd | Conwy | 2024 |
| 1COUNSEL Limited | London | 2019 |
| 1CRM Ltd | London | 2007 |
| 1D Accounts (Chester) Ltd | Chester | 2024 |
| 1D Agency Ltd | Manchester | 2018 |
| 1D Promotions Limited | Reading | 2022 |
| 1DA Limited | Pinner | 2010 |
| 1DAVEROBBO Limited | Altrincham | 2025 |
| 1DAY Workout Systems Ltd | London | 2025 |
| 1DIRECTION Civil Engineering Ltd. | Basildon | 2013 |
| 1DP Investment Management Ltd | Southampton | 2024 |
| 1DREAMS2REALITY Limited | Dunstable | 2011 |
| 1E Systems Limited | Cardiff | 2014 |
| 1E-APOSTILLE Ltd | Crawley | 2020 |
| 1E3X Limited | Leeds | 2019 |
| 1FRL Limited | Lindford | 2018 |
| 1G Dynamics Limited | Royston, Hertfordshire | 2017 |
| 1GIGLABS Ltd | London | 2026 |
| 1GM Consultancy Limited | Glasgow | 2024 |
| 1HQ Limited | Reading | 1993 |
| 1HQ Solutions Limited | London | 2016 |
| 1HUMANITY Ltd | Ilford | 2015 |
| 1I2US Ltd | Watford | 2017 |
| 1INSURER Holdings Limited | Birmingham | 2016 |
| 1K Enterprises Ltd | Huddersfield | 2012 |
| 1KC Barristers Chambers Ltd | Nottingham | 2018 |
| 1KC Chambers LLP | Birmingham | 2020 |
| 1KINGS5 Ltd | Banbury | 2019 |
| 1KLT Consultancy Ltd | Winsford | 2025 |
| 1LAW Investments Ltd | Walsall | 2025 |
| 1LE Consulting Ltd | Manchester | 2025 |
| 1LIFE Accounting Ltd | Craigavon | 2026 |
| 1LS Risk Consultants Ltd | Dorchester | 2018 |
| 1MB Limited | Ormskirk | 2015 |
| 1MEDSERV Ltd | Mitcham | 2018 |
| 1MFM Ltd | London | 2025 |
| 1NE Project Solution Limited | Leicestershire | 2006 |
| 1NECAD Ltd | London | 2025 |
| 1NEOF6IX Ltd | London | 2023 |
| 1NORTHFIELD Limited | Harrow | 2014 |
| 1NOTION Mgmt Ltd | London | 2024 |
| 1NVEST Limited | London | 2011 |
| 1OAK Photographic Limited | Northampton | 2014 |
| 1OFFICE Group Ltd | London | 2013 |
| 1OO2 Limited | Stockport | 2020 |
| 1OVMANY Ltd | Bromley | 2020 |
| 1P602E-19 Ltd | Watford | 2024 |
| 1PLANETDESIGN Limited | London | 2024 |
| 1PLANETINFRA Ltd | Sevenoaks | 2022 |
| 1POINT23 Limited | Tavistock | 2024 |
| 1PREMIER Ltd | London | 2023 |
| 1R Consulting Limited | Uxbridge | 2017 |
| 1RENE Limited | Warrington | 2015 |
| 1RJ Consulting Limited | St. Albans | 2026 |
| 1SEVEN Sports Management Group Ltd | London | 2020 |
| 1ST & Green Limited | London | 2021 |
| 1ST 2 Call Limited | Coventry | 2001 |
| 1ST 4 Accounts Limited | Hitchin | 2003 |
| 1ST 4 Warehouse Design Limited | Leicester | 2024 |
| 1ST 4IMMIGRATION Limited | London | 2010 |
| 1ST a Removals Limited | Edgware | 2002 |
| 1ST Accountancy (Leeds) Limited | | 2002 |
| 1ST Accountancy and Bookkeeping Services Ltd. | Harrow | 2016 |
| 1ST Accountancy Solutions Ltd | Knaresborough | 1999 |
| 1ST Accountants Ltd | Morden | 2017 |
| 1ST Accounting & Business Services Limited | Nottingham | 2012 |
| 1ST Accounting Solutions Limited | London | 2010 |
| 1ST Accounts (UK) Limited | Gillingham | 2012 |