EVENT 304 Open/Male 12 /Under 50m Butterfly - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Cameron MILNE | 11 | Deepings | |
| 4 | 2 | Siddharth SUTHAN | 9 | Co Lincoln P | 1:30.00 |
| 5 | 4 | Daniel GODDARD | 9 | Grantham | 1:10.00 |
| 6 | 5 | Sebastian MADDISON | 12 | Co Lincoln P | 1:10.00 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 6 | Theodor BULAT | 10 | Co Lincoln P | 1:08.42 |
| 2 | 7 | Zaid OMRAN | 11 | Co Lincoln P | 1:05.44 |
| 3 | 8 | William CASH | 11 | Deepings | 1:03.45 |
| 4 | 9 | Alexander SAUNDERS | 12 | Co Lincoln P | 1:01.92 |
| 5 | 10 | Louis WRIGHT | 10 | Grantham | 1:00.00 |
| 6 | 11 | Zachary TOMLINSON | 10 | Co Lincoln P | 58.32 |
| 7 | 12 | Sam RHOADES | 12 | Co Lincoln P | 57.92 |
| 8 | 13 | Inambao LUNGU | 10 | Lincoln Vulc | 56.88 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 14 | Thomas WHITTLE | 12 | Grantham | 55.90 |
| 2 | 16 | Benjamin SHEARN | 10 | Grantham | 53.82 |
| 3 | 17 | Jude SMITH | 11 | Lincoln Vulc | 53.33 |
| 4 | 18 | James BACON | 10 | Grantham | 52.00 |
| 5 | 19 | Toby BROWN | 11 | Deepings | 51.78 |
| 6 | 20 | Harry MELDRUM | 12 | Co Lincoln P | 50.61 |
| 7 | 21 | Arthur SAMMUT | 11 | Co Lincoln P | 49.72 |
| 8 | 22 | Jacob STAPLES | 12 | Lincoln Vulc | 49.08 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 24 | Derrin BROCKLEBANK | 10 | Grantham | 48.80 |
| 2 | 26 | Harry BEASTALL | 12 | Co Lincoln P | 47.38 |
| 3 | 27 | Benjamin GODDARD | 11 | Grantham | 47.33 |
| 4 | 28 | Freddie HIRST | 9 | Grantham | 47.30 |
| 5 | 29 | M PARAPIJONAVICIUS | 10 | Grantham | 44.90 |
| 6 | 30 | Barnaby DURANT | 10 | Grantham | 44.49 |
| 7 | 31 | Thomas KINNEAR | 12 | Grantham | 44.40 |
| 8 | 32 | Kai HILAROWICZ | 11 | Co Lincoln P | 44.25 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 33 | Henry DOLAN | 10 | Grantham | 42.40 |
| 2 | 34 | Ryan BARGH | 11 | Co Lincoln P | 41.85 |
| 3 | 35 | Elliot GLEAVE | 11 | Grantham | 41.72 |
| 4 | 36 | Callum LOYNES | 12 | Co Lincoln P | 41.53 |
| 5 | 37 | Finley WEST | 12 | Co Lincoln P | 41.37 |
| 6 | 38 | Evan NIXON | 12 | Lincoln Vulc | 41.22 |
| 7 | 39 | Arlo HAMER | 11 | Co Lincoln P | 41.19 |
| 8 | 40 | Bobby WALLIS | 11 | Co Lincoln P | 41.04 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 41 | Jonathan GBYLICZEK | 12 | Co Lincoln P | 40.99 |
| 2 | 42 | Oscar WOOD | 10 | Lincoln Vulc | 40.38 |
| 3 | 43 | Zachary WILSON | 12 | Lincoln Vulc | 40.01 |
| 4 | 44 | George LEONARD | 11 | Grantham | 39.94 |
| 5 | 45 | Toby EDMONDSON | 9 | Grantham | 39.37 |
| 6 | 46 | Yu Ching CHEUNG | 12 | Grantham | 38.78 |
| 7 | 47 | Leo BARNETT | 12 | Grantham | 38.76 |
| 8 | 48 | Henry WILLERTON | 10 | Boston | 38.17 |
| Heat Number - 7 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 50 | Joshua KIM | 11 | Grantham | 37.34 |
| 2 | 52 | Thomas HILLSON | 10 | Grantham | 36.20 |
| 3 | 54 | Oliver CLARKE | 11 | Deepings | 36.06 |
| 4 | 56 | Cole COOPER | 12 | Co Lincoln P | 34.40 |
| 5 | 55 | Stanley THURLOW | 11 | Lincoln Vulc | 35.10 |
| 6 | 53 | Oliver WILKINSON | 11 | Lincoln Vulc | 36.17 |
| 7 | 51 | Samuel NICHOLS | 12 | Grantham | 36.80 |
| 8 | 49 | Dan PALMER | 11 | Co Lincoln P | 38.13 |