| Under-15 Boys 300 Metres |
| 37.09 | Rob Page | Windsor, Slough, Eton & Hounslow AC | Manchester (SC) | 09/09/2012 |
| 36.24 | Joseph Massimo | Crawley AC | Kingston | 24/05/2014 |
| 36.17 | Joseph Massimo | Crawley AC | Kingston | 14/06/2014 |
| 35.21 | Joseph Massimo | Crawley AC | Birmingham | 12/07/2014 |
| 34.81 | Amir Sultan-Edwards | Blackheath & Bromley Harriers AC | Birmingham | 14/07/2018 |
| KEY |
| | i Indoor performance | |
| | * Old specification javelin | |
| | 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. |
