EVENT 402 Open/Male 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | James MOORE | 14 | Dunstable | |
| 4 | 4 | Stanley ALWAY | 11 | Verulam | |
| 5 | 2 | Abhimanyu KULKARNI | 12 | Amersham | |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 5 | Daniel GUIMARAES | 11 | Team Luton | 6:56.30 |
| 2 | 7 | George HING | 11 | Bedford SS | 6:05.00 |
| 3 | 10 | Ian ILIEV | 13 | Camden Swiss | 5:52.00 |
| 4 | 12 | Yaroslav SEMKIN | 13 | Co Milton K | 5:49.36 |
| 5 | 11 | Kuba KOPEC | 11 | Bedford SS | 5:50.00 |
| 6 | 8 | Arthur WAINWRIGHT | 11 | Bedford SS | 6:05.00 |
| 7 | 6 | Ismail AHMED WAGAN | 11 | Putteridge | 6:12.11 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 14 | Saul EDWARDS | 14 | Bedford SS | 5:42.92 |
| 2 | 17 | Jacob EDGELL | 15 | Verulam | 5:34.40 |
| 3 | 20 | Khaled ALLAM | 13 | Bedford SS | 5:25.00 |
| 4 | 22 | Noah HUTCHINGS | 13 | Camden Swiss | 5:22.97 |
| 5 | 21 | Charlie BRAMMER | 14 | Co Milton K | 5:24.36 |
| 6 | 18 | George HEARN | 14 | Dunstable | 5:33.80 |
| 7 | 16 | Austin CHRISTOPHER | 11 | Newport Pag | 5:34.78 |
| 8 | 13 | Max HART | 11 | Verulam | 5:48.80 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 24 | Zoran BUTORAC | 13 | Camden Swiss | 5:18.84 |
| 2 | 27 | Ethan HUNTLEY | 13 | Team Luton | 5:14.60 |
| 3 | 30 | Christos ROUMELIOTIS | 14 | Newport Pag | 5:04.10 |
| 4 | 32 | Daniel DALY | 13 | Camden Swiss | 4:59.83 |
| 5 | 31 | Solomon DENT | 15 | Bedford SS | 5:03.40 |
| 6 | 28 | Matthew HORTON | 14 | Dunstable | 5:09.13 |
| 7 | 26 | Riley MARTIN | 13 | Newport Pag | 5:17.60 |
| 8 | 23 | Thomas MCMASTER-IRONS | 14 | Bedford SS | 5:19.93 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 34 | Oliver GIRVAN | 17 | Bedford SS | 4:56.29 |
| 2 | 36 | Dillan CRONIN | 14 | Bark & Dagen | 4:50.60 |
| 3 | 38 | Jason GHOLAMI | 15 | Camden Swiss | 4:49.37 |
| 4 | 40 | Ethan DICK | 14 | Newport Pag | 4:43.40 |
| 5 | 39 | Malachy HITCHCOCK | 16 | Camden Swiss | 4:48.70 |
| 6 | 37 | Finn MATHERS | 13 | Camden Swiss | 4:50.60 |
| 7 | 35 | Luc BONFIGLIO | 13 | Camden Swiss | 4:54.53 |
| 8 | 33 | Daniel TALBOT | 14 | Aylesbury | 4:56.69 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 43 | Daniel DICK | 17 | Newport Pag | 4:35.64 |
| 2 | 46 | Leonardo DIALLO | 15 | Camden Swiss | 4:26.29 |
| 3 | 48 | Cameron JONES | 18 | Bedford SS | 4:24.45 |
| 4 | 50 | Benjamin GUTHRIE | 17 | Co Milton K | 4:12.96 |
| 5 | 49 | Henry GILLAM | 14 | Camden Swiss | 4:23.60 |
| 6 | 47 | Ryan CLOSE | 16 | Bedford SS | 4:24.98 |
| 7 | 45 | Ellis BUNCE | 16 | Aylesbury | 4:27.06 |
| 8 | 42 | Vincent WUN | 14 | Camden Swiss | 4:38.44 |