EVENT 504 Boys 10 Yrs/Over 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 3 | 1 | George Prince | 10 | Hatfield | 6:06.51 |
| 4 | 3 | Ryan Wall | 11 | Royston | 5:49.34 |
| 5 | 2 | Igor Mordeja | 11 | Cheshunt | 5:50.28 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 2 | 5 | Nathanial Mapley | 12 | Co St Albans | 5:42.32 |
| 3 | 7 | Koby Cornwell | 11 | Potters Bar | 5:41.16 |
| 4 | 9 | Ethan Howard | 11 | Potters Bar | 5:35.58 |
| 5 | 8 | Joshua Ellis | 12 | Hatfield | 5:36.56 |
| 6 | 6 | Marko Borgis | 12 | Stevenage | 5:42.06 |
| 7 | 4 | William Fawcett | 11 | Watford SC | 5:45.97 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 11 | Jason Hicks | 12 | Watford SC | 5:32.80 |
| 2 | 13 | Theo Lim | 12 | Watford SC | 5:29.96 |
| 3 | 15 | Joseph Sutton | 13 | Watford SC | 5:26.31 |
| 4 | 17 | Jamie Ismatullaev | 12 | Watford SC | 5:24.80 |
| 5 | 16 | Max Hill | 12 | Stevenage | 5:25.13 |
| 6 | 14 | Joshua Heesom | 13 | Potters Bar | 5:28.49 |
| 7 | 12 | Joel Pietersen | 11 | Hatfield | 5:30.52 |
| 8 | 10 | Jake Moore | 12 | Potters Bar | 5:34.51 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 19 | Thomas Godfrey | 12 | Co St Albans | 5:19.22 |
| 2 | 21 | Henry Newbury-Kemp | 13 | Hemel Hemp | 5:17.79 |
| 3 | 23 | Lucas Hartley | 11 | Hatfield | 5:17.16 |
| 4 | 25 | Max Robertson | 14 | Hatfield | 4:56.61 |
| 5 | 24 | Enzo Lim | 13 | Watford SC | 4:56.84 |
| 6 | 22 | Cub Maddison | 12 | Hatfield | 5:17.35 |
| 7 | 20 | Thomas Hooper | 13 | Co St Albans | 5:17.99 |
| 8 | 18 | Charles Taverner | 13 | Watford SC | 5:21.24 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 27 | James Gisborne | 13 | Bishop Stort | 4:52.42 |
| 2 | 29 | Arvin Rodriguez | 14 | Watford SC | 4:48.40 |
| 3 | 31 | Ketan Rach | 14 | Watford SC | 4:46.76 |
| 4 | 33 | Ciaran Cook | 15 | Co St Albans | 4:44.68 |
| 5 | 32 | Alexander Horne | 15 | Co St Albans | 4:45.64 |
| 6 | 30 | Alfie Francis | 15 | Potters Bar | 4:46.78 |
| 7 | 28 | George Williams | 14 | Harpenden | 4:50.29 |
| 8 | 26 | Samuel Pyefinch | 13 | Tring | 4:53.43 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 35 | Joshua Bridgeland | 15 | Hatfield | 4:42.53 |
| 2 | 37 | Mattias Morse | 15 | Hemel Hemp | 4:34.42 |
| 3 | 39 | Edward Jex | 15 | Co St Albans | 4:32.36 |
| 4 | 41 | Zane Batt | 15 | Cheshunt | 4:30.94 |
| 5 | 40 | Thomas Stanbury | 17 | Potters Bar | 4:32.11 |
| 6 | 38 | Ethan Sutton | 16 | Watford SC | 4:33.77 |
| 7 | 36 | Luke Pestaille | 15 | Hatfield | 4:36.57 |
| 8 | 34 | Peter Soczewka | 13 | Hatfield | 4:42.69 |
| Heat Number - 7 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 43 | Daniel Murtagh | 15 | Hatfield | 4:27.57 |
| 2 | 45 | Yannik Wilson | 16 | Harpenden | 4:26.43 |
| 3 | 47 | Michael Klimaszewski | 14 | Hatfield | 4:20.41 |
| 4 | 49 | Thomas Cadenhead | 16 | Co St Albans | 4:18.53 |
| 5 | 48 | Ayotobi Laguda | 16 | Hatfield | 4:20.26 |
| 6 | 46 | William Loveman | 18 | Co St Albans | 4:25.55 |
| 7 | 44 | Nicholas Botha | 16 | Bishop Stort | 4:26.92 |
| 8 | 42 | Thomas Ogden | 14 | Bishop Stort | 4:30.26 |
| Heat Number - 8 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 51 | Harrison Lees | 17 | Watford SC | 4:15.67 |
| 2 | 53 | Michael Ripper | 17 | Co St Albans | 4:13.03 |
| 3 | 55 | Ralph Muncer | 17 | Co St Albans | 4:07.10 |
| 4 | 57 | Max Jelfs | 17 | Hatfield | 4:01.55 |
| 5 | 56 | Luke Sugden | 19 | Hatfield | 4:02.78 |
| 6 | 54 | Jude Liddiard | 17 | Co St Albans | 4:12.91 |
| 7 | 52 | Callum Wollaston | 17 | Cheshunt | 4:14.53 |
| 8 | 50 | James Chennells | 17 | Berkhamsted | 4:18.50 |