EVENT 209 Mens Open 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Cat | Club/Country | Time |
| 3 | 1 | Mark EVENS | 23 | S14 | Bor of Brox | 5:25.78 |
| 4 | 3 | Oskar FARKAS | 14 | | Co Cambridge | 4:21.10 |
| 5 | 2 | Thomas BELCHER | 16 | | Modernian | 4:21.70 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Cat | Club/Country | Time |
| 2 | 5 | Harry SAUNDERS | 17 | | Newmarket | 4:21.09 |
| 3 | 7 | Mehdi EL MANSAR | 15 | | Bishop Stort | 4:14.20 |
| 4 | 9 | Joseph WELLS | 20 | | West Norfolk | 4:11.60 |
| 5 | 8 | Jude HILLS | 14 | | Thurrock | 4:12.10 |
| 6 | 6 | George WHITEMAN | 15 | | Co Peterboro | 4:20.30 |
| 7 | 4 | Nicholas BOTHA | 17 | | Bishop Stort | 4:21.09 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Cat | Club/Country | Time |
| 1 | 11 | Ben BLOWERS | 17 | | Co Norwich | 4:09.70 |
| 2 | 13 | Joe COOPER | 15 | | teamipswich | 4:08.60 |
| 3 | 15 | Nathan WOODROW | 16 | | Co Norwich | 4:07.40 |
| 4 | 17 | Samuel ROSE | 16 | | St Felix Sch | 4:06.31 |
| 5 | 16 | Maxwell GEORGE | 16 | | Hatfield | 4:06.60 |
| 6 | 14 | Noah JAMESON NEAL | 15 | | Basildon Ph | 4:07.60 |
| 7 | 12 | Owen WEBSTER | 16 | | St Felix Sch | 4:09.12 |
| 8 | 10 | Jordan CATCHPOLE | 20 | S14 | Co Norwich | 4:10.90 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Cat | Club/Country | Time |
| 1 | 19 | James SPEERS | 16 | | Basildon Ph | 4:06.02 |
| 2 | 21 | Joshua FOWLES | 20 | | Witham Dolph | 4:04.80 |
| 3 | 23 | Henry PEARCE | 17 | | Co Peterboro | 4:03.25 |
| 4 | 25 | Michael KLIMASZEWSKI | 15 | | Hatfield | 4:01.43 |
| 5 | 24 | Jude LIDDIARD | 18 | | Co St Albans | 4:02.90 |
| 6 | 22 | Samuel PECK | 19 | | Co Cambridge | 4:04.17 |
| 7 | 20 | Myles TURNER | 19 | | West Suffolk | 4:05.10 |
| 8 | 18 | Callum WOLLASTON | 18 | | Bor of Brox | 4:06.29 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Cat | Club/Country | Time |
| 1 | 27 | Jacques BONSELL | 20 | | Co Cambridge | 3:58.36 |
| 2 | 29 | Lewis BINNING | 16 | | Basildon Ph | 3:57.90 |
| 3 | 31 | Nathan WELLS | 21 | | West Norfolk | 3:51.87 |
| 4 | 33 | Regan LLOYD | 22 | | teamipswich | 3:47.30 |
| 5 | 32 | Nathan HUGHES | 19 | | Hatfield | 3:49.60 |
| 6 | 30 | Myles ROBINSON-YOUNG | 17 | | Co Peterboro | 3:57.43 |
| 7 | 28 | Matthew WRIGHT | 21 | | Team Luton | 3:58.04 |
| 8 | 26 | Ralph MUNCER | 18 | | Co St Albans | 4:00.30 |