EVENT 203 Open/Male 100m Butterfly - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Richard LEONOVS | 11 | Wisbech | 2:12.55 |
| 4 | 3 | Marcus VALENTE | 12 | Wisbech | 2:02.40 |
| 5 | 2 | Maximillian BALSEVICS | 10 | Wisbech | 2:11.66 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 2 | 5 | George BROTHERSTON | 15 | Wellingboro | 1:48.99 |
| 3 | 7 | Theo VANDOROS | 12 | Melton M'bry | 1:47.00 |
| 4 | 9 | Michal KOCHANOWICZ | 12 | Corby | 1:41.82 |
| 5 | 8 | Noah REDWOOD-MOORE | 12 | Melton M'bry | 1:44.80 |
| 6 | 6 | Gregory CROSS | 12 | Melton M'bry | 1:47.80 |
| 7 | 4 | Spencer CROSS | 10 | Melton M'bry | 2:01.80 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 11 | Harley MULLER | 13 | Wisbech | 1:38.50 |
| 2 | 13 | Oscar CUTMORE | 12 | Corby | 1:37.70 |
| 3 | 15 | Oscar PAWLOWSKI | 11 | Corby | 1:34.60 |
| 4 | 17 | Harry TOMPKINS | 13 | Market Har | 1:29.80 |
| 5 | 16 | Oliver TRENWITH | 12 | Corby | 1:34.60 |
| 6 | 14 | Jamie MASON | 16 | Corby | 1:37.26 |
| 7 | 12 | George HATWOOD | 14 | Wellingboro | 1:37.80 |
| 8 | 10 | Richard ANDERSON | 13 | Wellingboro | 1:41.80 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 19 | Zak HESKETH | 15 | Rushden | 1:27.20 |
| 2 | 21 | Jakub SIEDLAK | 14 | Corby | 1:22.72 |
| 3 | 23 | Kevin VARGA | 12 | Co Leicester | 1:21.80 |
| 4 | 25 | Ben DAVIES | 15 | Corby | 1:18.46 |
| 5 | 24 | Laurence WICKINS | 13 | Market Har | 1:20.00 |
| 6 | 22 | Wojciech WALACH | 15 | Corby | 1:22.16 |
| 7 | 20 | T NEDELCU-PAVELIUC | 13 | Wellingboro | 1:27.20 |
| 8 | 18 | Jacob URE | 13 | March | 1:28.50 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 27 | Austin HUNT | 15 | Melton M'bry | 1:16.10 |
| 2 | 29 | Alexandru IERINA | 15 | Kettering | 1:11.70 |
| 3 | 31 | Laurenzio CIOLAN | 15 | Corby | 1:09.70 |
| 4 | 33 | Finlay UNDERWOOD | 16 | Rushden | 1:08.90 |
| 5 | 32 | Tyler HOLLYMAN | 18 | Corby | 1:09.42 |
| 6 | 30 | Daniel TOMPKINS | 16 | Market Har | 1:10.70 |
| 7 | 28 | Ronnie BOOKER | 16 | Wellingboro | 1:14.90 |
| 8 | 26 | Aiden HORNE | 13 | Corby | 1:16.70 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 35 | Ryan DOYLE | 14 | Kettering | 1:07.10 |
| 2 | 37 | Ben NUTTER | 20 | Melton M'bry | 1:02.00 |
| 3 | 39 | Curtis MINNEY | 20 | Kettering | 1:01.00 |
| 4 | 41 | Ethan SOPPETT-MOSS | 16 | Corby | 55.60 |
| 5 | 40 | M VASCONCELLOS-BLANCH | 17 | Rushden | 57.74 |
| 6 | 38 | Daniel DOYLE | 17 | Kettering | 1:01.50 |
| 7 | 36 | Elliott BARKER | 18 | Nene Valley | 1:07.10 |
| 8 | 34 | Lewis REYNOLDS | 18 | Nene Valley | 1:08.85 |