| 1MAFX Limited | Milton Keynes | 2018 |
| 1MAI Ltd | London | 2023 |
| 1MAN-AI Ltd | Ruislip, | 2025 |
| 1MBR Limited | Manchester | 2025 |
| 1MGAMES Limited | London | 2025 |
| 1MKT Ltd | London | 2020 |
| 1MOMA Ltd | Sale | 2016 |
| 1MT Games Ltd | Edinburgh | 2021 |
| 1MYLE Ltd. | London | 2011 |
| 1N Technologies Limited | London | 2025 |
| 1NE Opportunity Limited | Leigh On Sea | 2019 |
| 1NE4ALLMEDIA Productions Ltd | Stoke-On-Trent | 2024 |
| 1NM Ltd | London | 2026 |
| 1NO2 Limited | London | 2006 |
| 1NSIDEOUT IT Solutions Limited | Manchester | 2013 |
| 1NSOURCE Ltd | Reading | 2023 |
| 1NV Limited | Ilford | 2017 |
| 1OAK Consulting Ltd | London | 2018 |
| 1OFF Media Ltd | London | 2022 |
| 1OH1DESIGNS Ltd | Godalming | 2025 |
| 1ON1 Consultancy Ltd | London | 2014 |
| 1ONEGS Ltd | Pinner | 2025 |
| 1PARTCARBON Ltd | Edinburgh | 2012 |
| 1PB Ltd | London | 2026 |
| 1PCS Limited | Northampton | 2004 |
| 1PD Ltd | Chichester | 2023 |
| 1PERCENTLAB Solutions Ltd | Ruislip, | 2025 |
| 1PESWA Ltd | Swindon | 2019 |
| 1PICK Ltd | Stoke-On-Trent | 2025 |
| 1PIXELMORE Ltd | Burton-On-Trent | 2015 |
| 1PLACE1CLOUD Limited | Redditch | 2021 |
| 1PLATFORM App Ltd | Manchester | 2026 |
| 1PLEX Limited | Cambridge | 2011 |
| 1PN4 Limited | Sutton | 2025 |
| 1POINT21 Limited | London | 2016 |
| 1POINT4 Ltd | Covent Garden | 2004 |
| 1POINT5 Technologies Ltd | Cambridge | 2021 |
| 1POINT6 Ltd | Manchester | 2025 |
| 1POINT61 Consulting Limited | Altrincham | 2024 |
| 1POINTMANAGEMENT Ltd | London | 2016 |
| 1QG Group Limited | London | 2024 |
| 1REAL Ltd | London | 2026 |
| 1ROOF Ltd | Southampton | 2006 |
| 1S Consulting Ltd | London | 2023 |
| 1SAIF (UK) Ltd | London | 2025 |
| 1SELF Health Ltd | Reading | 2023 |
| 1SIM Ltd | London | 2024 |
| 1SPATIAL Group Limited | Cambridge | 2003 |
| 1SPATIAL Holdings Limited | Cambridge | 2004 |
| 1SPATIAL Limited | Cambridge | 2005 |
| 1SRCREATIONS Limited | London | 2026 |
| 1SS Limited | Glasgow | 2023 |
| 1ST - Interactive Design Limited | London | 1996 |
| 1ST 4 Connect Limited | Dagenham | 2016 |
| 1ST 4 FUN Ltd | Birmingham | 2016 |
| 1ST 4 Projects Limited | Wokingham | 2008 |
| 1ST AD Chris Kelly Ltd | Worthing | 2025 |
| 1ST ADE Ltd | Southend-On-Sea | 2003 |
| 1ST Adtube Limited | London | 2016 |
| 1ST Advance Limited | Wokingham | 2002 |
| 1ST Aerials 'R' US Ltd | Verwood | 2014 |
| 1ST Audio Ltd | Alsager | 2024 |
| 1ST Born Solutions Ltd | London | 2013 |
| 1ST British Technology Solutions (UK) Limited | Northampton | 2018 |
| 1ST Business Connections Ltd | Preston | 2020 |
| 1ST Business Marketing Ltd | Cardiff | 2025 |
| 1ST Byte IT Solutions Limited | York | 2008 |
| 1ST Call Aerials Ltd | New Romney | 2019 |
| 1ST Call I.T. Limited | Bolton | 2005 |
| 1ST Call Install Limited | Bristol | 2002 |
| 1ST Call KB Aerials Limited | Cranbrook | 2003 |
| 1ST Call Mortgage & Protection Ltd | Rugeley | 2015 |
| 1ST Call Support Ltd | Hampshire | 2006 |
| 1ST Callcom Limited | Sheffield | 2000 |
| 1ST Choice Ixbrl Limited | Maldon | 2011 |
| 1ST Choice Reporting Ltd | Shrewsbury | 2015 |
| 1ST Class Aerial & Satellite Systems Limited | Borehamwood | 2009 |
| 1ST Class Consulting Services Ltd | Edinburgh | 2023 |
| 1ST Class Productions Ltd | Thames Ditton | 2009 |
| 1ST Clean Limited | Bristol | 2017 |
| 1ST Cloud Technology Ltd | Sunderland | 2008 |
| 1ST Code Ltd | London | 2021 |
| 1ST Connect Group Limited | Bournemouth | 2000 |
| 1ST Connect Limited | Poole | 2010 |
| 1ST Connect Services Ltd | Edinburgh | 2018 |
| 1ST Content Global Ltd | London | 2025 |
| 1ST Digital Ltd | London | 2025 |
| 1ST Direct Computer Services Ltd | Leyland | 2007 |
| 1ST Education Limited | Polegate | 2019 |
| 1ST Eleven Limited | London | 2017 |
| 1ST Energy Technologies Ltd | Liverpool | 2023 |
| 1ST for Creative Limited | Malpas | 2006 |
| 1ST Freight Limited | Romford | 2006 |
| 1ST Furnace Technologies Limited | Tamworth | 2015 |
| 1ST Impact Games Limited | Lytham St. Annes | 2016 |
| 1ST Impression Limited | Orpington | 2009 |
| 1ST IT Limited | Luton | 2017 |
| 1ST Leads Limited | Manchester | 2016 |
| 1ST Link Limited | Enfield | 2017 |
| 1ST Live Ltd | London | 2024 |