| 1ST Land Services Limited | Wetherby | 2021 |
| 1ST Leisure Limited | Hartlepool | 2002 |
| 1ST Local Window Repair Ltd | London | 2026 |
| 1ST Loft Ltd | London | 2020 |
| 1ST Logic Electrical Installations and Control Systems Limited | Poole | 2009 |
| 1ST London Ltd | London | 2019 |
| 1ST Look Contractor Services Ltd | Ashford | 2026 |
| 1ST Look Roofing Ltd | Dunmow | 2014 |
| 1ST Maintain Ltd | London | 2025 |
| 1ST Maintenance (Hove) Limited | Hove | 2009 |
| 1ST Maintenance Limited | Brixham | 2009 |
| 1ST Move Civil Engineering Limited | Rotherham | 2004 |
| 1ST NRG Ltd | Petersfield | 2022 |
| 1ST One Limited | Warwickshire | 2007 |
| 1ST One Plumbing and Heating Ltd | Edgware | 2019 |
| 1ST Option Construction Ltd | Barnet | 2024 |
| 1ST Option Roofing Limited | Wolverhampton | 2015 |
| 1ST Plant Hire Ltd | Leeds | 2007 |
| 1ST Plasterers and Painters Ltd | Maidenhead | 2017 |
| 1ST Platinum Homes Ltd | Ilford | 2018 |
| 1ST Platinum Investments Ltd | Brentwood | 2011 |
| 1ST Plumbers Ltd | London | 2023 |
| 1ST Plumbing Solutions Ltd | Rayleigh | 2019 |
| 1ST Point Electrical Services Limited | Bexleyheath | 2024 |
| 1ST Point Utilities & Reinstatement Ltd | Exeter | 2025 |
| 1ST Porter Call Limited | Chippenham | 2015 |
| 1ST Premier Damp Proofing Ltd | Grimsby | 2021 |
| 1ST Property Specialists Ltd | Morden | 2023 |
| 1ST Rate Fencing Ltd | Weston Super Mare | 2021 |
| 1ST Rate Group Ltd | Ringwood | 2019 |
| 1ST Rate Ltd | Weymouth | 2003 |
| 1ST Rate Roofing Ltd | Ringwood | 2019 |
| 1ST Reset Limited | Hertfordshire | 2004 |
| 1ST Response Building Maintenance Ltd | London | 2022 |
| 1ST Response Demolition Limited | Brentwood | 2025 |
| 1ST Response Heating and Plumbing Ltd | Basingstoke | 2005 |
| 1ST Response Heating Services Limited | Basildon | 2002 |
| 1ST Response Hire and Sales Limited | Rayleigh | 2017 |
| 1ST Response Maintenance Ltd | London | 2025 |
| 1ST Roofing and Cladding Limited | Edinburgh | 2021 |
| 1ST Roofing Services Ltd | Bedford | 2023 |
| 1ST Roofing Specialists Limited | Epsom | 2006 |
| 1ST Scaffolding (Berkshire) Ltd | Reading | 2011 |
| 1ST Scenic Windows Limited | Orpington | 2013 |
| 1ST Scope Ltd | London | 2024 |
| 1ST Seed Property Ltd | Brechin | 2021 |
| 1ST Select Build UK Ltd | Haslemere | 2019 |
| 1ST Services Devon Limited | Exeter | 2003 |
| 1ST Shield Maintenance Ltd | Manchester | 2022 |
| 1ST Site Building & Landscaping Ltd | Stratford-Upon-Avon | 2018 |
| 1ST Smart Choice Limited | Southall | 2024 |
| 1ST Smart Systems Ltd | Northampton | 2025 |
| 1ST Solar Ltd | Hamilton | 2012 |
| 1ST Solo Ductwork Services Limited | Harrow | 2000 |
| 1ST Solution Contractors Ltd | London | 2011 |
| 1ST Solution GAS and Plumbing Ltd | London | 2026 |
| 1ST Solution Services Ltd | London | 2015 |
| 1ST Sparks (SW) Ltd | Exeter | 2025 |
| 1ST Stop Bathroom Ltd | Chorley | 2006 |
| 1ST Stop Builders Ltd | London | 2019 |
| 1ST Stop Building & Renovations Ltd | Bracknell | 2026 |
| 1ST Stop Building Services Ltd | Bracknell | 2018 |
| 1ST Stop Constructions Ltd | Rochdale | 2025 |
| 1ST Stop Contractors Limited | London | 2017 |
| 1ST Stop Interiors Ltd | Redruth | 2005 |
| 1ST Stop Maintenance Ltd | Wickford | 2018 |
| 1ST Stop Plumbing and Heating Limited | Reading | 2006 |
| 1ST Stop Security Systems Ltd | London | 2018 |
| 1ST Storage UK Limited | Leeds | 2000 |
| 1ST Stroke Decorators Ltd | London | 2024 |
| 1ST Team Roof Consultants Ltd | Cambridge | 2025 |
| 1ST Time FIX GAS, Plumbing & Heating Ltd | Sutton Coldfield | 2019 |
| 1ST Trust Roofing Ltd | Morecambe | 2024 |
| 1ST UK Roofing & Building Ltd | London | 2019 |
| 1ST Vacuum Glass Ltd | Royston | 2023 |
| 1ST View Developments Limited | Andover | 2024 |
| 1ST View Home Improvements Limited | Edinburgh | 2018 |
| 1ST Viking Ltd | Waterlooville | 2026 |
| 1ST Well Limited | Welwyn Garden City | 2025 |
| 1ST Westminster Builders Limited | Waterlooville | 2003 |
| 1ST Windows Ltd | Stockton-On-Tees | 2024 |
| 1ST-FIX Limited | Luton | 2025 |
| 1ST-STOP Property Maintenance Ltd | Waltham Cross | 2025 |
| 1ST-SURFACE Limited | West Byfleet | 1998 |
| 1ST. Choice Plumbing & Heating Limited | Glasgow | 2007 |
| 1ST.CZECH Made Ltd | Stafford | 2019 |
| 1ST4FENCING Services Ltd | Farnham | 2022 |
| 1STBUILDERS4U Ltd | Hayes | 2021 |
| 1STEP Go Limited | Leeds | 2018 |
| 1STFIT Construction Ltd | London | 2026 |
| 1STFLOOR Limited | Milton Keynes | 2021 |
| 1STOPDESIGNANDBUILD Ltd | London | 2023 |
| 1STPROPERTIESUK Ltd | Birmingham | 2020 |
| 1STPROSERVICES Limited | Morden | 2025 |
| 1TA Holdings Limited | Bedford | 2024 |
| 1TECH Building Services Ltd | Bromsgrove | 2025 |
| 1TIME Windows Ltd | Bromley | 2024 |
| 1TO1 Construction Ltd | Colchester | 2024 |
| 1TR Development Ltd | London | 2022 |
| 1TRX Ltd | Cardiff | 2015 |