EVENT 47 Boy Open 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 2 | C Bernal Mezzetti | 13 | Poole | 5:48.55 |
| 2 | 4 | Gabriel Petrov | 16 | S Bournem'th | 5:31.13 |
| 3 | 6 | George Gillett | 16 | Seagulls SC | 5:20.29 |
| 4 | 8 | Stephen Quine | 17 | Blandford | 5:18.27 |
| 5 | 7 | Finley Lock | 14 | Seagulls SC | 5:19.94 |
| 6 | 5 | Frederick Beasley | 15 | Poole | 5:23.03 |
| 7 | 3 | George Honor | 14 | Seagulls SC | 5:36.57 |
| 8 | 1 | Mark Talalaykin | 14 | Poole | 5:56.25 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 10 | Hugo Young | 14 | S Bournem'th | 5:15.70 |
| 2 | 12 | Jamie Workman | 15 | Bourmth Coll | 4:58.68 |
| 3 | 14 | Lawrence Elliott | 17 | Seagulls SC | 4:46.46 |
| 4 | 16 | Sonny Chamberlain-Hyde | 19 | Seagulls SC | 4:36.96 |
| 5 | 15 | Robbie Hemmings | 18 | Poole | 4:40.11 |
| 6 | 13 | Oliver Jones | 17 | Poole | 4:52.18 |
| 7 | 11 | Arron Hopkins | 15 | Poole | 5:05.84 |
| 8 | 9 | Oliver Deretz | 16 | Poole | 5:16.10 |