| 1 | Lockers Park School | 189 pupils | Independent · Boarding | Hemel Hempstead, East of England | — ISI · Good |
| 2 | Edge Grove School | 396 pupils | Independent · Day | Watford, East of England | — ISI · Good |
| 3 | Beechwood Park School | 478 pupils | Independent · Boarding | St Albans, East of England | — ISI · Good |
| 4 | Old Buckenham Hall School | 190 pupils | Independent · Boarding | Ipswich, East of England | — ISI · Good |
| 5 | Lochinver House School | 324 pupils | Independent · Day | Potters Bar, East of England | — ISI · Good |
| 6 | Berkhamsted Prep and Pre-Prep School | 555 pupils | Independent · Day | Berkhamsted, East of England | — |
| 7 | Heath Mount School | 505 pupils | Independent · Boarding | Hertford, East of England | — ISI · Good |
| 8 | Aldwickbury School | 368 pupils | Independent · Boarding | Unknown, East of England | — ISI · Good |
| 9 | Alleyn Court Preparatory School | 244 pupils | Independent · Day | Southend-on-Sea, East of England | — ISI · Excellent |
| 10 | Barnardiston Hall Preparatory School | 232 pupils | Independent · Boarding | Haverhill, East of England | — ISI · Good |
| 11 | Glebe House School | 191 pupils | Independent · Boarding | Hunstanton, East of England | — ISI · Good |
| 12 | Beeston Hall School | 168 pupils | Independent · Boarding | Cromer, East of England | — ISI · Good |
| 13 | Orwell Park School | 210 pupils | Independent · Boarding | Ipswich, East of England | — ISI · Good |
| 14 | Polam School | 96 pupils | Independent · Day | Bedford, East of England | — ISI · Excellent |
| 15 | Merchant Taylors' Prep School | 365 pupils | Independent · Day | Rickmansworth, East of England | — ISI · Good |
| 16 | York House School | 360 pupils | Independent · Day | Unknown, East of England | — ISI · Good |
| 17 | Langley Preparatory School At Taverham Hall | 323 pupils | Independent · Day | Norwich, East of England | — ISI · Good |
| 18 | South Lee School | 189 pupils | Independent · Day | Bury St Edmunds, East of England | — ISI · Good |
| 19 | Manor Lodge School | 463 pupils | Independent · Day | Shenley, East of England | — ISI · Good |
| 20 | Littlegarth School | 296 pupils | Independent · Day | Colchester, East of England | — ISI · Good |
| 21 | Duncombe School | 271 pupils | Independent · Day | Hertford, East of England | — ISI · Good |
| 22 | Radlett Preparatory School Ltd | 266 pupils | Independent · Day | Herts, East of England | — ISI · Good |
| 23 | Oaklands School | 256 pupils | Independent · Day | Loughton, East of England | — ISI · Good |
| 24 | Fairstead House | 221 pupils | Independent · Day | Unknown, East of England | — ISI · Good |
| 25 | Widford Lodge School | 206 pupils | Independent · Day | Chelmsford, East of England | — ISI · Good |