EVENT 315 Open/Male 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 2 | Mark Evens | 30 | S14 | Hitchin | 5:32.30 |
| 2 | 4 | Rex Harrison | 15 | | Stowmarket | 4:32.95 |
| 3 | 6 | Jacob Schultz | 15 | | Co Cambridge | 4:27.42 |
| 4 | 8 | Jacob Wild | 15 | | Newmarket | 4:25.59 |
| 5 | 7 | Joseph Subba | 15 | | Co St Albans | 4:26.87 |
| 6 | 5 | Corey Hare | 20 | S14 | Deben | 4:31.63 |
| 7 | 3 | Heath Harrison | 15 | | Stowmarket | 4:34.03 |
| 8 | 1 | Jacob Dessoy | 18 | S8 | Thurrock | 6:15.30 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 10 | Lochlan Shaw | 16 | | Flitwick | 4:25.33 |
| 2 | 12 | Kian Ptolomey | 16 | | Putteridge | 4:24.50 |
| 3 | 14 | Alfie Page | 17 | | Co Cambridge | 4:23.58 |
| 4 | 16 | Isaac Buchan | 17 | | Co Norwich | 4:23.20 |
| 5 | 15 | Oliver Meier | 16 | | Biggleswade | 4:23.24 |
| 6 | 13 | William Hughes | 16 | | Chelmsford | 4:24.30 |
| 7 | 11 | Christian Ludwig | 15 | | Basildon Ph | 4:24.60 |
| 8 | 9 | Thomas Fenwick | 15 | | Hatfield | 4:25.50 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 18 | Oliver Fuller | 16 | | Co Cambridge | 4:22.05 |
| 2 | 20 | Tyler Stone | 16 | | Co Norwich | 4:21.10 |
| 3 | 22 | Ashton Blake | 17 | | Basildon Ph | 4:20.43 |
| 4 | 24 | Lucas Day | 17 | | Rochford | 4:19.52 |
| 5 | 23 | Jacopo Agosti | 15 | | Co Cambridge | 4:20.12 |
| 6 | 21 | Daniel De Filippo | 17 | | Flitwick | 4:20.60 |
| 7 | 19 | Jed Millin | 18 | | Stowmarket | 4:21.79 |
| 8 | 17 | Charlie Stott | 17 | | Co St Albans | 4:23.18 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 26 | Ryan Wimpenny | 16 | | Cheshunt | 4:19.03 |
| 2 | 28 | Daniel Thompson | 19 | | Thurrock | 4:17.40 |
| 3 | 30 | Jacob Bacon | 16 | | Co Peterboro | 4:15.44 |
| 4 | 32 | Kian Lee | 18 | | Co Peterboro | 4:15.42 |
| 5 | 31 | Ethan Wallis | 16 | | Norwich Swan | 4:15.44 |
| 6 | 29 | Csanad Rehus | 17 | | Co Peterboro | 4:15.65 |
| 7 | 27 | Perrin Ma | 15 | | Hatfield | 4:18.40 |
| 8 | 25 | Xavier Zerban | 15 | | Biggleswade | 4:19.40 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 34 | Benjamin Palmer | 15 | | Bishop Stort | 4:15.36 |
| 2 | 36 | Luke Owens | 16 | | Putteridge | 4:14.65 |
| 3 | 38 | George Carter | 18 | | Co Cambridge | 4:12.58 |
| 4 | 40 | Kets Yah-Khai | 17 | | Hatfield | 4:09.74 |
| 5 | 39 | Oliver Fenwick | 17 | | Hatfield | 4:12.40 |
| 6 | 37 | Daniel Moyses | 20 | | Co Peterboro | 4:14.38 |
| 7 | 35 | Jamie Wilson | 17 | | West Norfolk | 4:15.04 |
| 8 | 33 | Janos Csepely | 15 | | teamipswich | 4:15.40 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 42 | Zak Fellows | 17 | | Co St Albans | 4:09.35 |
| 2 | 44 | Oscar Hunter | 17 | | Norwich Swan | 4:07.92 |
| 3 | 46 | Conor Mint | 17 | | Basildon Ph | 4:06.12 |
| 4 | 48 | Daniel Belsey | 18 | | Hatfield | 4:00.50 |
| 5 | 47 | Samuel Rose | 23 | | Norwich Swan | 4:04.77 |
| 6 | 45 | Robert Fenner | 18 | | Basildon Ph | 4:07.20 |
| 7 | 43 | Adam O'Neal | 18 | | Bedford SS | 4:08.30 |
| 8 | 41 | Ethan Knights | 15 | | teamipswich | 4:09.70 |