| Castle Stables Management Company Limited | Long Bennington | 2024 |
| Castle Street Bodmin Management Limited | Tavistock | 2021 |
| Castle Street Hertford Management Limited | Hertford | 2002 |
| Castle Street Wallingford Management Company Limited | Henley-On-Thames | 2009 |
| Castle Syke & Sandy Gate (Pontefract) Management Company Limited | Hemel Hempstead | 2025 |
| Castle Terrace (Hillsborough) Management Company Limited | Hillsborough | 2016 |
| Castle Terrace Proprietors Committee Ltd | Bridge Of Weir | 2024 |
| Castle Trading Limited | London | 1981 |
| Castle Upton Management Company Limited | Coleraine | 1990 |
| Castle Vale Management Company Limited | Preston | 1997 |
| Castle View (Doncaster) Management Company Limited | Doncaster | 2002 |
| Castle View (Green Lanes) Management Limited | London | 1998 |
| Castle View (Netherton) Management Company Limited | York | 2022 |
| Castle View (Netley Abbey) Property Management Limited | Netley Abbey | 2020 |
| Castle View (Newbury) Management Company Limited | Wokingham | 2015 |
| Castle View (Old Sarum) Management Company Limited | Salisbury | 2009 |
| Castle View Close (West Midlands) Management Company Limited | Shrewsbury | 2017 |
| Castle View Gardens Management Company Limited | Uxbridge | 1987 |
| Castle View House (Upnor) Limited | Rochester | 2020 |
| Castle View Management Company (NO.1) Limited | St Annes On Sea | 2003 |
| Castle View Management Company (Scarborough) Limited | Scarborough | 2006 |
| Castle View Management Company (Tonbridge) Limited | Marden | 1999 |
| Castle View Meadow Community Interest Company | Ludlow | 2020 |
| Castle View Parking Limited | Yarmouth | 2024 |
| Castle View Residents Association Limited | Bourne End | 1969 |
| Castle View RTM Company Limited | Windsor | 2009 |
| Castle Village Residents Limited | St Ives | 2015 |
| Castle Walk (Stansted) Management Company Ltd | Stansted | 2018 |
| Castle Walk Limited | Wadhurst | 1980 |
| Castleacre Freehold Company Limited | London | 2001 |
| Castleart Limited | London | 1980 |
| Castlebar Road Estate (Ealing) Limited | Beaumont | 1969 |
| Castlebrere Limited | East Sussex | 1993 |
| Castlecatt Landscape Management Limited | Coleraine | 2004 |
| Castlecroft House Management Company Limited | Bromsgrove | 2003 |
| Castlecroft Management Limited | Bury | 1988 |
| Castleday Residents Association Limited | London | 1984 |
| Castledene Property Management (Nottingham) Limited | Nottingham | 2025 |
| Castledine Court Management Company Limited | Mansfield | 2005 |
| Castledine Limited | Chislehurst | 1989 |
| Castledyke Management Company Limited | Plymouth | 2000 |
| Castlefield Commercial Property Services Ltd | Manchester | 2021 |
| Castlefield Gate Management Company Limited | Manchester | 2001 |
| Castlefield Locks Management Limited | Manchester | 2003 |
| Castlefield Midlands Limited | Burton Upon Trent | 2005 |
| Castlefield Park (Harlington) Management Company Limited | Leighton Buzzard | 2024 |
| Castlefields (Coinsborough) Management Company Limited | Hemel Hempstead | 2003 |
| Castlefields (Phase 2) Management Company Limited | Doncaster | 2005 |
| Castlefields Bingley (Management) Limited | Ilkley | 2018 |
| Castleford Maintenance Ltd | Okehampton | 2021 |
| Castlegate & Mowbray Park Management Company Limited | Bishop Auckland | 2014 |
| Castlegate (Ballyclare) Land Management Ltd | Ballyclare | 2026 |
| Castlegate (Ballymena) Property Management Limited | Ballyclare | 2020 |
| Castlegate (Hadleigh) RTM Company Limited | Westcliff-On-Sea | 2012 |
| Castlegate Chorleywood Management Co Limited | Leighton Buzzard | 2014 |
| Castlegate Management Company (Flats) Limited | Lancaster | 1994 |
| Castlegate Securities 2 Limited | Salford | 2019 |
| Castlegate Securities Limited | Salford | 2019 |
| Castlegrange Maintenance Management Limited | Carrickfergus | 2001 |
| Castlegroom Limited | Orpington | 1999 |
| Castlehead Gardens Management Co. Limited | Leeds | 1980 |
| Castlehill Estate Management Company Limited | Carrickfergus | 2007 |
| Castlehill Farm Management Company Limited | Newtownabbey | 2001 |
| Castlehill Place Management Limited | Belfast | 2003 |
| Castlehill Property Management Company Limited | Limavady | 2018 |
| Castlehill Residential Lettings Limited | Ayr | 2009 |
| Castlehill Wood Management Company Limited | Belfast | 2018 |
| Castlehold Lane Management Company Limited | Newport | 2016 |
| Castlelodge Gardens Land Management Ltd | Ballyclare | 2022 |
| Castlemain Management Company Limited | Dorchester | 2016 |
| Castlemans NO.2 Residents Company Limited | Upham | 1994 |
| Castlemans Residents Company Limited | Edgware | 1989 |
| Castlemead (953) Trowbridge Management Company Limited | York | 2016 |
| Castlemead (Persimmon 950) Town Trowbridge Limited | York | 2016 |
| Castlemead (Persimmon 964) Town Trowbridge Limited | York | 2016 |
| Castlemead Court Management Company Limited | Windsor | 1986 |
| Castlemead Management Company (2000) Limited | Christchurch | 2000 |
| Castlemead Washford Management Limited | Minehead | 2017 |
| Castlemount Residents Limited | Brighton | 1964 |
| Castlepoint Residents Company Limited | Lower Upnor | 2020 |
| Castlereagh House (2022) Ltd | Harrow | 2022 |
| Castleridge Management Company Limited | Newcastle | 1986 |
| Castleridge Property Management Limited | Tunbridge Wells | 1993 |
| Castlerigg Court Limited | Wallasey | 1989 |
| Castlerocklands Management Limited | Belfast | 2000 |
| Castleroe Management Company Limited | Limavady | 2008 |
| Castles Green Management Company Limited | Tyne & Wear | 1983 |
| Castleside Ltd | Dover | 2022 |
| Castlesproperties Ltd | Cardiff | 2019 |
| Castlestead (Pateley Bridge) Management Company Limited (the) | Harrogate | 1961 |
| Castleton Close Limited | Sutton | 1990 |
| Castleton Court (Belfast) Management Company Ltd | Belfast | 2023 |
| Castleton Court (Haverfordwest) Management Company Limited | Salisbury | 2014 |
| Castleton Court (Leeds) Limited | Rhyl | 2017 |
| Castleton Court (Paddington) Limited | London | 1971 |
| Castleton Court (Surbiton)Residents Association Limited | Chessington | 1962 |
| Castleton Court Management Company (Leeds) Ltd | Tockholes | 2023 |
| Castleton Grange (EYE) Residents Management Company Limited | York | 2023 |
| Castleton Meadows Management Company Limited | Norwich | 2006 |
| Castleton Properties Limited | Tunbridge Wells | 1987 |