EVENT 131 Men 15 Yrs/Over 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 1 | Rio Rogers | 17 | S14 | Basildon Ph | 4:55.78 |
| 2 | 3 | Maddox Roberts | 15 | | Witham Dolph | 4:43.39 |
| 3 | 5 | Harry Stagg | 15 | | Basildon Ph | 4:41.98 |
| 4 | 7 | Max Arnold | 15 | | Harlow Pen | 4:40.50 |
| 5 | 6 | Tom Wood | 15 | | Chelmsford | 4:40.50 |
| 6 | 4 | Dylan Morris | 15 | | Watford SC | 4:42.60 |
| 7 | 2 | Louis James | 15 | | Norwich Swan | 4:44.24 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 9 | Samuel Walsh | 15 | | Witham Dolph | 4:38.59 |
| 2 | 11 | Daniel Kendall | 15 | | Co Ely | 4:38.12 |
| 3 | 13 | Jago Derrington | 15 | | Bishop Stort | 4:35.59 |
| 4 | 15 | Roan Brennan | 15 | S9 | Basildon Ph | 4:31.80 |
| 5 | 14 | Matthew Monie | 16 | | Co Cambridge | 4:32.07 |
| 6 | 12 | Matthew Riddle | 16 | | Thurrock | 4:37.24 |
| 7 | 10 | Jamie Joshua | 15 | | Hatfield | 4:38.39 |
| 8 | 8 | Daniel McGuinness | 15 | | Basildon Ph | 4:39.40 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 17 | Daniel Clayton | 15 | | teamipswich | 4:29.39 |
| 2 | 19 | William Tozer | 18 | | West Suffolk | 4:25.02 |
| 3 | 21 | Austin Lillywhite | 18 | | Biggleswade | 4:24.41 |
| 4 | 23 | Joe Fletcher | 19 | | Stowmarket | 4:21.75 |
| 5 | 22 | Harley West | 17 | | Basildon Ph | 4:23.53 |
| 6 | 20 | Mark Milburn | 16 | | Colchester | 4:25.00 |
| 7 | 18 | Nikita Charykin | 15 | | Thurrock | 4:26.70 |
| 8 | 16 | Elliot Gladwell | 16 | | teamipswich | 4:30.22 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 25 | Matthew Brown | 16 | | Stowmarket | 4:21.42 |
| 2 | 27 | Olivier Vedrenne | 16 | | Co Norwich | 4:20.20 |
| 3 | 29 | George Whiteman | 17 | | Co Peterboro | 4:14.37 |
| 4 | 31 | Jack Sangster | 20 | | Modernian | 4:10.10 |
| 5 | 30 | Joseph Wells | 22 | | West Norfolk | 4:11.60 |
| 6 | 28 | William Ellard | 15 | | St Felix Sch | 4:18.65 |
| 7 | 26 | Matthew Baker | 15 | | West Suffolk | 4:20.70 |
| 8 | 24 | Jack Pallant | 17 | | Team Waveney | 4:21.69 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 33 | Joe Cooper | 17 | | teamipswich | 4:08.22 |
| 2 | 35 | Callum Wollaston | 20 | | Co St Albans | 4:06.29 |
| 3 | 37 | Michael Klimaszewski | 17 | | Hatfield | 4:01.43 |
| 4 | 39 | Nathan Wells | 23 | | West Norfolk | 3:49.12 |
| 5 | 38 | Lewis Binning | 18 | | Basildon Ph | 3:57.90 |
| 6 | 36 | Myles Turner | 21 | | West Suffolk | 4:03.63 |
| 7 | 34 | Noah Jameson Neal | 17 | | Basildon Ph | 4:07.60 |
| 8 | 32 | Ben Blowers | 19 | | Co Norwich | 4:09.70 |