| 1 | Willis Limited London Turnover £1.1bn | £615.0M | £1.1bn |
| 2 | Cabot G.B. Limited Penarth | £102.0M | — |
| 3 | Darag Insurance UK Limited London | £36.2M 2022 accounts | — |
| 4 | Arag PLC Caerphilly Turnover £17.0M | £28.9M 2022 accounts | £17.0M |
| 5 | Samsung Fire & Marine Insurance Company of Europe Ltd. London | £26.3M 2019 accounts | — |
| 6 | Kingsbridge Risk Solutions Limited Tewkesbury | £22.3M 2024 accounts | — |
| 7 | Darag Legacy UK Ltd London | £21.2M 2022 accounts | — |
| 8 | Fortegra Insurance UK Ltd. London Turnover £0 | £19.7M 2024 accounts | £0 |
| 9 | Squaretrade Limited London Turnover £76.3M | £17.3M 2024 accounts | £76.3M |
| 10 | James Hallam Limited Dorking Turnover £44.8M | £15.1M 2024 accounts | £44.8M |
| 11 | Lexham Insurance Consultants Limited Diss Turnover £27.0M | £14.5M 2024 accounts | £27.0M |
| 12 | Lifesearch Limited Whiteley Turnover £62.2M | £12.6M | £62.2M |
| 13 | Ripe Insurance Services Limited Stockport Turnover £26.8M | £12.5M 2022 accounts | £26.8M |
| 14 | Cover-More Insurance Services Ltd Uxbridge Turnover £5.5M | £8.7M | £5.5M |
| 15 | Animal Friends Insurance Services Limited Amesbury | £8.4M 2023 accounts | — |
| 16 | Talbot and Muir Limited Salisbury Turnover £5.8M | £6.5M 2021 accounts | £5.8M |
| 17 | Inigo Managing Agent Limited London Turnover £413.7k | £5.4M 2020 accounts | £413.7k |
| 18 | Investacc Pension Administration Limited Carlisle Turnover £5.8M | £5.2M 2023 accounts | £5.8M |
| 19 | Pharon Independent Financial Advisers Limited Canterbury Turnover £6.0M | £4.8M 2024 accounts | £6.0M |
| 20 | JRP Insurance Management Limited London | £4.7M 2022 accounts | — |
| 21 | Shepherd Compello Ltd London Turnover £5.9M | £4.6M | £5.9M |
| 22 | Rock Insurance Services Limited Crawley Turnover £12.1M | £4.3M 2024 accounts | £12.1M |
| 23 | Ggfi Limited London Turnover £1.5M | £4.2M | £1.5M |
| 24 | T L Dallas & Co Limited Bradford Turnover £16.2M | £4.1M | £16.2M |
| 25 | Alan Blunden & Co. Ltd London Turnover £25.5M | £4.0M 2023 accounts | £25.5M |
| 26 | Kbis Limited London | £3.9M 2024 accounts | — |
| 27 | Evolin Broking Limited London | £3.7M | — |
| 28 | Touchstone Underwriting Limited Dorking Turnover £6.3M | £3.5M 2024 accounts | £6.3M |
| 29 | Bridge Insurance Brokers Limited London | £3.3M 2025 accounts | — |
| 30 | Castelan Limited Weston Super Mare Turnover £10.7M | £3.1M 2022 accounts | £10.7M |
| 31 | Autohome Insurance Limited Northampton Turnover £1.0M | £3.0M | £1.0M |
| 32 | Well Dunn Limited Manchester Turnover £11.5M | £2.8M 2025 accounts | £11.5M |
| 33 | W. Denis (Insurance Brokers) PLC Leeds | £2.8M | — |
| 34 | BJP Insurance Brokers Limited Leeds Turnover £5.4M | £2.4M 2022 accounts | £5.4M |
| 35 | Find Insurance NI Ltd Carrickfergus | £2.4M 2023 accounts | — |
| 36 | Skybound Financial Planning Limited Fareham Turnover £2.9M | £2.2M 2023 accounts | £2.9M |
| 37 | Claims Settlement Agencies Limited London | £2.2M 2021 accounts | — |
| 38 | BMW (UK) Pensions Services Limited Farnborough Turnover £1.4M | £2.0M 2020 accounts | £1.4M |
| 39 | Ancile Insurance Group Ltd. London | £1.8M 2024 accounts | — |
| 40 | Philip T English International Financial Services Limited Banbury Turnover £2.4M | £1.8M 2025 accounts | £2.4M |
| 41 | Applewood Independent Ltd Bromsgrove | £1.8M | — |
| 42 | Nowell & Richards Insurance Services Limited Leeds | £1.7M 2021 accounts | — |
| 43 | M & D H Insurance Services Ltd Bristol | £1.6M 2022 accounts | — |
| 44 | Seascope Insurance Services Limited Turnover £3.7M | £1.6M | £3.7M |
| 45 | Bannerman Rendell Limited London | £1.5M 2024 accounts | — |
| 46 | David Holman Holdings Limited East Grinstead | £1.3M | — |
| 47 | Creative Benefit Solutions Limited London | £1.3M 2021 accounts | — |
| 48 | Coface UK Holdings Limited Watford Turnover £0 | £1.2M 2020 accounts | £0 |
| 49 | North Star Underwriting Limited London | £1.2M 2024 accounts | — |
| 50 | Anchorman Insurance Consultants Limited London | £1.1M 2022 accounts | — |
| 51 | London Market Claims Services Limited London Turnover £410.0k | £1.0M 2021 accounts | £410.0k |
| 52 | 247 Home Assist Limited Burnley | £993.3k | — |
| 53 | Greenwood Insurance Consultants Ltd. Blantyre | £819.2k 2021 accounts | — |
| 54 | Shipman Financial Planning Limited Exeter | £712.9k 2020 accounts | — |
| 55 | White Oak Underwriting Agency Limited London Turnover £4.0M | £697.2k 2024 accounts | £4.0M |
| 56 | Gilbert Wealth Limited Horsham | £487.8k 2025 accounts | — |
| 57 | Eggar Forrester Insurance Limited London | £472.3k | — |
| 58 | Tempo Partners Limited London | £458.9k 2023 accounts | — |
| 59 | Guaranteed Conveyancing Solutions Limited London Turnover £980.5k | £397.3k 2021 accounts | £980.5k |
| 60 | Kay International Public Limited Company London | £384.9k | — |
| 61 | W. Denis Credit Risks Limited Leeds | £333.3k | — |
| 62 | Butterworth Spengler Commercial Limited Leeds | £320.6k 2020 accounts | — |
| 63 | Buzzacott Financial Services Limited London Turnover £3.6M | £308.6k | £3.6M |
| 64 | Portcullis Financial Planning Limited Bromsgrove | £235.0k | — |
| 65 | Eppione Limited London Turnover £442.7k | £229.1k 2024 accounts | £442.7k |
| 66 | Capital Markets Underwriting Limited London | £217.4k 2022 accounts | — |
| 67 | Newline Group Services Limited London | £56.6k 2023 accounts | — |
| 68 | Stroll Insurance Services Limited Carrickfergus | £51.0k 2019 accounts | — |
| 69 | Cobalt Underwriting Services Limited London | £16.3k 2024 accounts | — |
| 70 | Milford Haven Port Authority PFP (General Partner) Limited Glasgow | £8.1k 2021 accounts | — |
| 71 | Moorhouse Group Limited Caerphilly Turnover £7.4k | £5.3k 2024 accounts | £7.4k |
| 72 | R&Q Reinsurance Company (UK) Limited London Turnover £474 | £2.8k | £474 |
| 73 | Moorhouse Group Holdings Limited Caerphilly | £175 2024 accounts | — |
| 74 | Bridgehaven Specialty UK Ltd London | £1 2021 accounts | — |
| 75 | Arcadian Risk Capital (UK) Ltd London | -£24.3k 2021 accounts | — |
| 76 | Node International Ltd London | -£84.2k 2019 accounts | — |
| 77 | MS Automotive (London) Limited London | -£108.7k 2024 accounts | — |
| 78 | J. Safra Sarasin Brokerage Limited London | -£1.0M 2024 accounts | — |
| 79 | Wesleyan Assurance Society | — | — |
| 80 | Cna Insurance Company Limited London | — | — |
| 81 | BA (GI) Limited London | — | — |
| 82 | Methodist Insurance Public Limited Company Gloucester | — | — |
| 83 | Britannia Steam Ship Insurance Association Limited(the) London | — | — |
| 84 | The London Steam-Ship Owners' Mutual Insurance Association Limited | — | — |
| 85 | Hadron UK Insurance Company Limited London | — | — |
| 86 | The Marine Insurance Company Limited London | — | — |
| 87 | Bai (Run-Off) Ltd London | — | — |
| 88 | The Prudential Assurance Company Limited London | — | — |
| 89 | The Standard Club UK Ltd London | — | — |
| 90 | Aviva International Insurance Limited London | — | — |
| 91 | The United Kingdom Mutual Steam Ship Assurance Association Limited London | — | — |
| 92 | Ecclesiastical Insurance Office Public Limited Company Gloucester | — | — |
| 93 | The Ocean Marine Insurance Company Limited Norwich | — | — |
| 94 | HSF Health Plan Limited | — | — |
| 95 | Aviva Insurance Limited | — | — |
| 96 | BHSF Limited Birmingham | — | — |
| 97 | Equitable Life Assurance Society,(the) Aylesbury | — | — |
| 98 | The London and Overseas Insurance Company Limited Leeds | — | — |
| 99 | The Chester Street Employers Association Limited Birmingham | — | — |
| 100 | Npa Insurance Limited St Albans | — | — |
| 101 | Hiscox Insurance Company Limited London | — | — |
| 102 | PA (GI) Limited Birmingham | — | — |
| 103 | Municipal Mutual Insurance Limited London | — | — |
| 104 | Cornish Mutual Assurance Company,limited Truro | — | — |
| 105 | Axa Insurance UK PLC London | — | — |
| 106 | Baptist Insurance Company PLC the Gloucester | — | — |
| 107 | Allianz Insurance PLC London | — | — |
| 108 | Sovereign Health Care Shipley | — | — |
| 109 | Chesnara Life (UK) Limited Preston | — | — |
| 110 | Xitus Insurance Limited London | — | — |
| 111 | Intact Insurance UK Limited London | — | — |
| 112 | Trafalgar Insurance Limited Surrey | — | — |
| 113 | The Dominion Insurance Company Limited Edinburgh | — | — |
| 114 | Royal & Sun Alliance Reinsurance Limited London | — | — |
| 115 | Salvation Army General Insurance Corporation Limited(the) Chelmsford | — | — |
| 116 | Arag Legal Expenses Insurance Company Limited Caerphilly | — | — |
| 117 | Steamship Mutual Underwriting Association Limited London | — | — |
| 118 | Gresham Insurance Company Limited Norfolk | — | — |
| 119 | National Farmers Union Mutual Insurance Society Limited(the) Warwickshire | — | — |
| 120 | United Kingdom Mutual War Risks Association Limited London | — | — |
| 121 | Lochain Patrick Insurance Brokers Ltd London | — | — |
| 122 | Ashdowns Limited Nr Ormskirk | — | — |
| 123 | NRG Victory Reinsurance Limited London | — | — |
| 124 | Legal and General Assurance Society Limited | — | — |
| 125 | Starr International Services (UK) Limited London | — | — |
| 126 | Gallagher Consultants (Healthcare) Limited London | — | — |
| 127 | Chaucer Syndicates Limited London | — | — |
| 128 | Lloyds Bank General Insurance Limited | — | — |
| 129 | Avon Insurance PLC Stratford Upon Avon | — | — |
| 130 | WPS Capital Ltd Cardiff | — 2020 accounts | — |
| 131 | Kelco Limited Warrington | — | — |
| 132 | Water Street Investments Limited | — | — |
| 133 | BP Pension Trustees Limited Middlesex | — | — |
| 134 | Ecclesiastical Life Limited Gloucester | — | — |
| 135 | British Aviation Insurance Company Limited London | — | — |
| 136 | Oic Run-Off Limited Leeds | — | — |
| 137 | Allianz Services (UK) Limited London | — | — |
| 138 | Medicash Health Benefits Limited Liverpool | — | — |
| 139 | Lancashire Syndicates Limited London | — | — |
| 140 | Boots Pensions Limited | — | — |
| 141 | Westfield Contributory Health Scheme Limited Sheffield | — | — |
| 142 | British Reserve Insurance Company Limited London | — | — |
| 143 | Teachers Assurance Company Limited Bournemouth | — | — |
| 144 | National House-Building Council Milton Keynes | — | — |
| 145 | Marks and Spencer Pension Trust Limited London | — | — |
| 146 | Ageas Insurance Limited Eastleigh | — | — |
| 147 | Trent Insurance Company Limited London | — | — |
| 148 | Bartlett & Company Limited Leeds | — | — |
| 149 | Harold Wilson (Insurances) Limited | — | — |
| 150 | South Shore Mutual Insurance Company Limited | — | — |
| 151 | Fairmead Insurance Limited Guildford | — | — |
| 152 | Starr Syndicate Management Limited London | — | — |
| 153 | The Scottish Lion Insurance Company Limited Perth | — | — |
| 154 | Nestle UK Pension Trust Ltd. York | — | — |
| 155 | British Airways Pension Trustees Limited Harmondsworth | — | — |
| 156 | River Thames Insurance Company Limited London | — | — |
| 157 | Western Provident Association Limited Taunton | — | — |
| 158 | Realty Insurances Limited London | — | — |
| 159 | Domestic & General Insurance PLC London | — | — |
| 160 | The United Kingdom Freight Demurrage and Defence Association Limited London | — | — |
| 161 | Northstandard Limited Newcastle Upon Tyne | — | — |
| 162 | The Exeter Cash Plan Exeter | — | — |
| 163 | Welsh Hospitals & Health Services Association Cardiff | — | — |
| 164 | Bolton and District Hospital Saturday Council Sheffield | — | — |
| 165 | Aig Europe (Services) Limited London | — | — |
| 166 | Gwent Hospitals Workmen's and Contributory Fund(the) Cardiff | — | — |
| 167 | Liverpool Victoria Life Company Limited | — | — |
| 168 | Covea Insurance PLC Halifax | — | — |
| 169 | Possfund Nominees Limited London | — | — |
| 170 | Rentokil Insurance Limited Crawley | — | — |
| 171 | Butcher, Robinson & Staples International Limited London | — | — |
| 172 | Howden Insurance Brokers Limited London | — | — |
| 173 | Tokio Marine Kiln Syndicates Limited London | — | — |
| 174 | Reassure Limited Telford Shropshire | — | — |
| 175 | Atlanta Insurance Intermediaries Limited Salford | — | — |
| 176 | DFDS Pension Limited Immingham | — | — |
| 177 | Integralife UK Limited London | — | — |
| 178 | LA Reunion Aerienne London Limited London | — | — |
| 179 | Paycare Wolverhampton | — | — |
| 180 | Brit Syndicates Limited London | — | — |
| 181 | National Casualty Company of America Limited London | — | — |
| 182 | Jelf Insurance Brokers Limited London | — | — |
| 183 | Hodge Life Assurance Company Limited London | — | — |
| 184 | Bartlett Wealth Management Ltd Leeds | — | — |
| 185 | Car Care Plan Limited Thornbury | — | — |
| 186 | Scottish Electrical Contractors Insurance Limited Midlothian | — | — |
| 187 | Wilson Insurance Broking Group Limited | — 2024 accounts | — |
| 188 | Allied Dunbar Assurance PLC Swindon | — | — |
| 189 | Transatlantic Life Assurance Company Limited | — | — |
| 190 | Covéa Life Limited Halifax | — | — |
| 191 | European Insurance and Reinsurance Brokers Limited London | — | — |
| 192 | Bartlett Group Limited Leeds | — | — |
| 193 | Miles Smith Limited London | — | — |
| 194 | Phoenix Life CA Limited Birmingham | — | — |
| 195 | Markel International Insurance Company Limited London | — | — |
| 196 | Lloyds Bank Insurance Services Limited | — | — |
| 197 | Travelers Management Limited London | — | — |
| 198 | Canada Life Limited London | — | — |
| 199 | Lifesure Group Limited London | — | — |
| 200 | Unum Limited Surrey | — | — |
| 201 | Threadneedle Pensions Limited London | — | — |
| 202 | Tokio Marine Kiln Insurance Limited London | — | — |
| 203 | Imi Pensions Trust Limited Birmingham | — | — |
| 204 | Prudential Pensions Limited London | — | — |
| 205 | Harel (UK) Ltd. London | — | — |
| 206 | Legal and General Assurance (Pensions Management) Limited London | — | — |
| 207 | Pinnacle Insurance Limited Borehamwood | — | — |
| 208 | Suffolk Life Annuities Limited Suffolk | — | — |
| 209 | Phoenix Life Limited Birmingham | — | — |
| 210 | Travelers Insurance Company Limited London | — | — |
| 211 | Qbe Underwriting Limited London | — | — |
| 212 | Mitsui Sumitomo Insurance Company (Europe), Limited London | — | — |
| 213 | Qbe European Services Limited London | — | — |
| 214 | JMG Insurance Brokers Limited Leeds | — | — |
| 215 | Community Reinsurance Corporation Limited London | — | — |
| 216 | Tenecom Limited London | — | — |
| 217 | Allianz Pension Fund Trustees Limited London | — | — |
| 218 | First Title Insurance PLC London | — | — |
| 219 | Renaissancere Syndicate Management Limited London | — | — |
| 220 | Suecia RE & Marine Insurance Company Limited London | — | — |
| 221 | Kenmore UK Ltd. Hemel Hempstead | — | — |
| 222 | Ahj Holdings Limited | — | — |
| 223 | C.J. Coleman & Company Limited London | — | — |
| 224 | Kirly Limited | — | — |
| 225 | Domestic & General Group Limited London | — | — |
| 226 | Colt Car Company Limited (The) London | — | — |
| 227 | Universities Superannuation Scheme Limited Liverpool | — | — |
| 228 | Riverstone Insurance (UK) Limited Brighton | — | — |
| 229 | U K Insurance Limited Leeds | — | — |
| 230 | Suffolk Life Pensions Limited Suffolk | — | — |
| 231 | TM Claims Service Europe Limited London Turnover £4.1M | — | £4.1M |
| 232 | Aspen Insurance UK Limited | — | — |
| 233 | Arthur J. Gallagher (UK) Limited London | — | — |
| 234 | Alwen Hough Johnson Limited | — | — |
| 235 | Oval Insurance Broking Limited London | — | — |
| 236 | Heath Lambert Limited London | — | — |
| 237 | Bimeh Iran Insurance Company (U.K.) Limited | — | — |
| 238 | Amtrust Specialty Limited London | — | — |
| 239 | Wausau Insurance Company (U.K.) Limited London | — | — |
| 240 | Kyoei Fire & Marine Insurance Co. (U.K.) Limited London | — | — |
| 241 | Butcher, Robinson & Staples Limited London | — | — |
| 242 | Munich RE Specialty Insurance (UK) Limited Manchester | — | — |
| 243 | Hardy (Underwriting Agencies) Limited London | — | — |
| 244 | Pet Plan Limited London | — | — |
| 245 | Cereal Partners U.K. Pension Trust Limited Welwyn Garden City | — | — |
| 246 | C.J. Coleman Holdings Limited London | — | — |
| 247 | Heddington Insurance (U.K.) Limited London | — | — |
| 248 | Munich RE Syndicate Limited London | — | — |
| 249 | Scor UK Company Limited London | — | — |
| 250 | Marco Gamma Limited London | — | — |
| 251 | Car Care Plan (Holdings) Limited Thornbury | — | — |
| 252 | Reassure Life Limited Telford | — | — |
| 253 | Hartford Underwriting Agency Limited London | — | — |
| 254 | The Royal Bank of Scotland Group Independent Financial Services Limited Edinburgh | — | — |
| 255 | M.A.H. (Ploddy) Limited Glos | — | — |
| 256 | Victor O. Schinnerer & Company Ltd. London | — | — |
| 257 | Reliance National Insurance Company (Europe) Limited London | — | — |
| 258 | BMS Group Limited London | — | — |
| 259 | Totalenergies Pension Company UK Limited London | — | — |
| 260 | JLT Specialty Limited London | — | — |
| 261 | H.W. Wood Limited London | — 2019 accounts | — |
| 262 | HCC International Insurance Company PLC London | — | — |
| 263 | Seventeen Group Limited Dorking | — | — |
| 264 | Acorn Insurance and Financial Services Limited Liverpool | — | — |
| 265 | Wesleyan Financial Services Limited | — | — |
| 266 | Ashbrooke Underwriting Services Limited London | — | — |
| 267 | Gard (UK) Limited London | — | — |
| 268 | Possfund Custodian Trustee Limited London | — | — |
| 269 | Leagold Limited London | — | — |
| 270 | Bell & Clements Limited London | — | — |
| 271 | Bell & Clements (London) Limited London | — | — |
| 272 | Astrenska Insurance Limited London | — | — |
| 273 | Catlin Risk Solutions Limited London | — | — |
| 274 | Cogent International Limited London | — | — |
| 275 | Nacora Insurance Brokers Limited Feltham | — | — |
| 276 | Qbe UK Limited London | — | — |
| 277 | China Taiping Insurance (UK) Co Ltd London | — | — |
| 278 | LV Protection Limited Dorset | — | — |
| 279 | Lincoln Insurance Services Limited London | — | — |
| 280 | Axa XL Underwriting Agencies Limited London | — | — |
| 281 | JCB Insurance Services Limited Staffordshire | — | — |
| 282 | Personal Assurance Public Limited Company Milton Keynes | — | — |
| 283 | London General Insurance Company Limited Crewe | — | — |
| 284 | Aioi Nissay Dowa Insurance Management Limited London | — | — |
| 285 | Beazley Furlonge Limited London | — | — |
| 286 | Sesame General Insurance Services Limited York | — | — |
| 287 | Geodis United Kingdom Limited Feltham | — | — |
| 288 | Asta Managing Agency Ltd London | — | — |
| 289 | RJ Kiln & Co. (No.2) Limited London | — | — |
| 290 | Atrium Underwriters Limited London | — | — |
| 291 | Domestic & General Services Limited London | — | — |
| 292 | CBC UK Limited London | — | — |
| 293 | Housing Association Property Mutual Limited London | — | — |
| 294 | Wren Insurance Association Limited(the) London | — | — |
| 295 | Collegiate Management Services Limited London | — | — |
| 296 | Brit Insurance Services Limited London | — | — |
| 297 | The Griffin Insurance Association Limited London | — | — |
| 298 | Markerstudy Insurance Services Limited Sevenoaks | — | — |
| 299 | Transportation Claims Limited Reading | — | — |
| 300 | Phoenix Wealth Trustee Services Limited Birmingham | — | — |