EVENT 401 Open/Male 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Liam TWINING | 13 | Dunstable | |
| 4 | 3 | Hanz Dylan MARCELO | 15 | Dunstable | |
| 5 | 2 | Fredrik STEEVES | 13 | Wycombe Dist | |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 5 | William JARRETT | 10 | TigersJersey | |
| 2 | 7 | Ho Yeung Desmond KWOK | 15 | Harpenden | |
| 3 | 10 | Theo RAWNSLEY | 10 | Harpenden | 6:36.40 |
| 4 | 12 | Maximilian PETRAVICH | 13 | Team Luton | 6:19.12 |
| 5 | 11 | Tyler LAVENDER | 12 | Team Luton | 6:30.29 |
| 6 | 9 | Tyatt COLE | 11 | Bo Southend | 6:52.30 |
| 7 | 6 | Elijah UNSWORTH | 10 | Team Luton | |
| 8 | 4 | Isaac GREEN | 14 | Wycombe Dist | |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 14 | Jack COX | 13 | Ealing | 5:53.70 |
| 2 | 16 | Casper WHITTAKER | 13 | Biggleswade | 5:34.60 |
| 3 | 18 | Samuel CHILDS | 13 | Berkhamsted | 5:23.74 |
| 4 | 22 | Mihailo VUCKOVIC | 14 | Ealing | 4:59.10 |
| 5 | 19 | Sami BOUKHTOUCHE | 13 | Ealing | 5:20.00 |
| 6 | 17 | Henry TAYLOR | 15 | Biggleswade | 5:27.12 |
| 7 | 15 | Dewi FORDYCE | 13 | Berkhamsted | 5:37.16 |
| 8 | 13 | Kit MANSFIELD | 13 | TigersJersey | 6:11.69 |