| Under-15 Girls 300 Metres |
| 44.22 | India Dryburgh | Walton AC | Lee Valley | 25/01/2015 |
| 44.12 | Amelia Bell | Kingston AC & Polytechnic Harriers | Lee Valley | 09/01/2016 |
| 45.36 | Arabella Wilson | Guildford & Godalming AC | Lee Valley | 12/01/2020 |
| 41.94 | Emma Fisher | Walton AC | Sheffield | 22/02/2020 |
| 41.50 | Gracelyn Kendeck | Croydon Harriers | Sheffield | 13/02/2022 |
| 40.84 | Holly Ryan | Shaftesbury Barnet Harriers | Sheffield | 10/02/2024 |
| 40.18 | Holly Ryan | Shaftesbury Barnet Harriers | Sheffield | 11/02/2024 |
| KEY |
| | mx Performance achieved in mixed sex race | |
| NOTE. A 3-character code between the club and the venue indicates that the athlete was not eligible to represent GB at the time of the performance but did have a Surrey County qualification. |
