EVENT 233 Open/Male 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Isaac Buchan | 15 | Co Norwich | 5:17.55 |
| 4 | 3 | Spencer Battisson | 16 | Team Waveney | 5:14.05 |
| 5 | 2 | Oliver Fenwick | 15 | Team Luton | 5:16.64 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 4 | Jamie Wilson | 15 | West Norfolk | 5:12.80 |
| 2 | 6 | Harry Bird | 15 | Putteridge | 5:10.70 |
| 3 | 8 | F Cleland Ferdin | 16 | Co Cambridge | 5:09.46 |
| 4 | 10 | Cillian O'Brien | 16 | Co Ely | 5:09.03 |
| 5 | 9 | Ryan Ingram | 16 | Co St Albans | 5:09.34 |
| 6 | 7 | Joshua Jones | 15 | West Norfolk | 5:10.50 |
| 7 | 5 | Finlay German | 15 | Co Cambridge | 5:11.65 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 12 | Csanad Rehus | 15 | Co Peterboro | 5:04.67 |
| 2 | 14 | Thomas Spelman | 17 | Stowmarket | 5:03.79 |
| 3 | 16 | Theodore Monk | 16 | Co Cambridge | 5:02.21 |
| 4 | 18 | B Macdonald-Williams | 16 | Bishop Stort | 5:00.56 |
| 5 | 17 | Daniel De Filippo | 15 | Flitwick | 5:00.70 |
| 6 | 15 | Harvey Isle | 19 | West Norfolk | 5:03.71 |
| 7 | 13 | Frank Lamb | 15 | Co Peterboro | 5:04.57 |
| 8 | 11 | Ashton Blake | 15 | Basildon Ph | 5:08.35 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 20 | Benjamin Every | 16 | St Felix Sch | 4:58.29 |
| 2 | 22 | Daniel Thompson | 17 | Thurrock | 4:56.98 |
| 3 | 24 | George Carter | 16 | Co Cambridge | 4:56.51 |
| 4 | 26 | Daniel Meier | 17 | Biggleswade | 4:55.41 |
| 5 | 25 | Marton Molnar | 15 | Co Cambridge | 4:56.33 |
| 6 | 23 | Finlay Neve | 16 | Co Norwich | 4:56.94 |
| 7 | 21 | Danylo Kravchenko | 15 | New Hall | 4:57.25 |
| 8 | 19 | Conor Mint | 15 | Basildon Ph | 4:58.60 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 28 | Daryl Rands | 27 | Colchester | 4:52.13 |
| 2 | 30 | Robert Fenner | 16 | Basildon Ph | 4:46.73 |
| 3 | 32 | Orlando Dearing | 16 | Co Peterboro | 4:45.90 |
| 4 | 34 | Daniel Moyses | 18 | Co Peterboro | 4:44.20 |
| 5 | 33 | Reece Burns | 16 | Chelmsford | 4:45.59 |
| 6 | 31 | Jack Barnard | 19 | Watford SC | 4:46.52 |
| 7 | 29 | Kian Lee | 16 | Co Peterboro | 4:48.35 |
| 8 | 27 | Daniel Holliss | 18 | Co St Albans | 4:52.98 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 36 | Ben Minister | 18 | Thurrock | 4:43.10 |
| 2 | 38 | Oscar Winterburn | 16 | teamipswich | 4:41.43 |
| 3 | 40 | Harrison Shaw | 17 | Flitwick | 4:37.10 |
| 4 | 42 | Nathan Wells | 26 | West Norfolk | 4:28.37 |
| 5 | 41 | Patch Robinson | 17 | teamipswich | 4:34.69 |
| 6 | 39 | Daniel McGuinness | 18 | Basildon Ph | 4:38.10 |
| 7 | 37 | Sandijs Cecins | 17 | Colchester | 4:42.21 |
| 8 | 35 | Samuel Jeffrey | 17 | Hatfield | 4:43.64 |