EVENT 301 Open/Male 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 2 | 1 | Henry RAITT | 11 | Corby | 7:08.90 |
| 3 | 3 | Harley MULLER | 13 | Wisbech | 6:36.28 |
| 4 | 5 | William ROBERTS | 26 | Peterbo SPG | 6:28.60 |
| 5 | 4 | William STEVENSON | 11 | Nene Valley | 6:29.55 |
| 6 | 2 | Mohamed JERID | 13 | Rushden | 6:50.36 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 7 | Oscar CUTMORE | 12 | Corby | 6:21.20 |
| 2 | 9 | Adam CHUCHRA | 10 | Wisbech | 6:08.33 |
| 3 | 11 | Jesunefe ABEKE | 15 | Corby | 5:52.90 |
| 4 | 13 | Oscar MULLER | 12 | Wisbech | 5:40.53 |
| 5 | 12 | Zakaria DAHMANI | 15 | Wisbech | 5:50.13 |
| 6 | 10 | Dorian MARAFKO | 15 | Corby | 5:59.40 |
| 7 | 8 | Oscar PAWLOWSKI | 11 | Corby | 6:13.26 |
| 8 | 6 | Hugo FLIKWEERT | 12 | Nene Valley | 6:28.03 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 15 | Benjamin WHITE | 14 | Rushden | 5:19.30 |
| 2 | 17 | Dylan BIELBY | 17 | Kettering | 5:03.00 |
| 3 | 19 | Connor ALLEN | 18 | Wellingboro | 4:40.14 |
| 4 | 21 | Finley DARE | 16 | Corby | 4:26.60 |
| 5 | 20 | M VASCONCELLOS-BLANCH | 17 | Rushden | 4:34.50 |
| 6 | 18 | Daniel MUSTATA | 14 | Corby | 4:54.32 |
| 7 | 16 | Wojciech WALACH | 15 | Corby | 5:13.59 |
| 8 | 14 | Oliver TRENWITH | 12 | Corby | 5:35.60 |