EVENT 104 Open/Male 100m Butterfly - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 2 | Joseph BROWN | 10 | Ealing | |
| 4 | 4 | Parker SMITH | 11 | Wycombe Dist | |
| 5 | 3 | Daniel NOON | 9 | Dunstable | |
| 6 | 1 | Thomas SMITH | 10 | Wycombe Dist | |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 6 | Ho Yeung Desmond KWOK | 15 | Harpenden | |
| 2 | 8 | Zachary LUDWELL | 13 | Dunstable | 1:51.07 |
| 3 | 10 | William JARRETT | 10 | TigersJersey | 1:44.97 |
| 4 | 12 | Nathaniel DOEDENS | 11 | Wycombe Dist | 1:31.08 |
| 5 | 11 | Kit MANSFIELD | 13 | TigersJersey | 1:37.39 |
| 6 | 9 | Alexandru ZAHARIA | 11 | Ealing | 1:47.30 |
| 7 | 7 | Louis WILLIAMS | 11 | TigersJersey | 1:58.85 |
| 8 | 5 | Kevin IRIMIA | 12 | Bletchley | |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 14 | Joshua WARD | 15 | Team Luton | 1:31.00 |
| 2 | 16 | Nathaniel NG | 15 | Ealing | 1:28.50 |
| 3 | 18 | Junsong LUO | 11 | Ealing | 1:24.46 |
| 4 | 20 | Victor MAITRET | 12 | Ealing | 1:21.60 |
| 5 | 19 | Filip BOCHENKO | 13 | Ealing | 1:23.70 |
| 6 | 17 | Matteo BALTAZAR | 12 | Wycombe Dist | 1:26.52 |
| 7 | 15 | Tyatt COLE | 11 | Bo Southend | 1:30.61 |
| 8 | 13 | Elijah UNSWORTH | 10 | Team Luton | 1:31.00 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 22 | Jack COX | 13 | Ealing | 1:16.88 |
| 2 | 24 | George DAVEY-CROUCH | 14 | Bo Southend | 1:13.90 |
| 3 | 26 | Ozan VELIOGLU | 16 | Saffron Wald | 1:12.00 |
| 4 | 28 | Hanz Dylan MARCELO | 15 | Dunstable | 1:10.78 |
| 5 | 27 | Casper WHITTAKER | 13 | Biggleswade | 1:11.20 |
| 6 | 25 | Franklin SHIELLS | 14 | Biggleswade | 1:12.50 |
| 7 | 23 | Tristan STRUC | 13 | Berkhamsted | 1:16.60 |
| 8 | 21 | Dewi FORDYCE | 13 | Berkhamsted | 1:20.31 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 30 | Sami BOUKHTOUCHE | 13 | Ealing | 1:08.40 |
| 2 | 32 | Henry TAYLOR | 15 | Biggleswade | 1:08.21 |
| 3 | 34 | Rafe LAWSON | 14 | Berkhamsted | 1:03.40 |
| 4 | 36 | Harry COOPER | 18 | Rochford | 58.71 |
| 5 | 35 | Mihailo VUCKOVIC | 14 | Ealing | 1:00.10 |
| 6 | 33 | Sebastian MILLER | 14 | Ealing | 1:05.20 |
| 7 | 31 | Lewis COX | 14 | Ealing | 1:08.40 |
| 8 | 29 | Samuel CHILDS | 13 | Berkhamsted | 1:08.54 |