EVENT 101 Open/Male 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Jonas Chor Hang TING | 10 | Verulam | |
| 4 | 3 | Tyler LAVENDER | 12 | Team Luton | 6:24.90 |
| 5 | 2 | Oliver PETCHEY | 13 | West Suffolk | 6:53.35 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 5 | David DE LA FUENTE | 15 | Bletchley | 6:14.23 |
| 2 | 7 | George GOSLING | 11 | Berkhamsted | 5:55.51 |
| 3 | 9 | Theo PAULL | 10 | Ascot Royals | 5:51.15 |
| 4 | 11 | Isaac VELLA | 13 | West Suffolk | 5:40.59 |
| 5 | 10 | Jack MAY | 13 | Linslade | 5:41.13 |
| 6 | 8 | Ismail AHMED WAGAN | 12 | Putteridge | 5:51.74 |
| 7 | 6 | Jaiden AMUSA | 11 | Team Luton | 6:10.32 |
| 8 | 4 | Elijah POWELL | 12 | Linslade | 6:18.40 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 14 | Marcus XU | 13 | Linslade | 5:23.20 |
| 2 | 16 | Charlie JONES | 16 | Bletchley | 5:20.72 |
| 3 | 18 | Jack BALLESTER | 15 | St Ives | 5:04.73 |
| 4 | 20 | Jack CANHAM | 14 | Team Luton | 4:38.47 |
| 5 | 19 | Ben GORING-FARROW | 14 | Linslade | 5:04.12 |
| 6 | 17 | Rafe LAWSON | 13 | Berkhamsted | 5:06.60 |
| 7 | 15 | Max HART | 12 | Verulam | 5:21.40 |
| 8 | 13 | Maximilian PETRAVICH | 12 | Team Luton | 5:33.96 |