| (1) | 40.02 | CBP | Holly Ryan | (Shaftesbury Barnet Harriers) | 1 FINAL | Kingsmeadow Stadium | 12 May 2024 |
| (2) | 40.39 | | Tia Garrard | (Kingston AC & Polytechnic Harriers) | 2 FINAL | Kingsmeadow Stadium | 12 May 2024 |
| (3) | 41.45 | CBP | Katie Sakaria | (Guildford & Godalming AC) | 1 FINAL | Kingsmeadow Stadium | 12 May 2019 |
| (4) | 41.77 | | Lily-Rose Brown | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 15 May 2022 |
| (5) | 41.81 | | Tia Garrard | (Kingston AC & Polytechnic Harriers) | 1 HEAT 2 | Kingsmeadow Stadium | 12 May 2024 |
| (6) | 42.09 | CBP | Katie Sakaria | (Guildford & Godalming AC) | 1 HEAT 1 | Kingsmeadow Stadium | 12 May 2019 |
| (7) | 42.18 | | Vivienne Jonczyk | (Hercules Wimbledon AC) | 1 FINAL | Kingsmeadow Stadium | 14 May 2023 |
| (8) | 42.20 | | Lily-Rose Brown | (Herne Hill Harriers) | 1 HEAT 1 | Kingsmeadow Stadium | 15 May 2022 |
| (9) | 42.22 | | Emma Fisher | (Walton AC) | 2 FINAL | Kingsmeadow Stadium | 12 May 2019 |
| (10) | 42.38 | | Grace Connor | (Guildford & Godalming AC) | 2 FINAL | Kingsmeadow Stadium | 15 May 2022 |
| |
| 10 performances of 42.38 or better. |
