EVENT 304 Open/Male 12 /Under 50m Butterfly - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 2 | 1 | George SPENCER | 9 | Grantham | |
| 3 | 2 | Ewan BELL | 10 | Lincoln Vulc | 1:31.25 |
| 4 | 3 | W POWELL-VREESWIJK | 10 | Grantham | 1:30.00 |
| 5 | 5 | Henry MOSS | 12 | Deepings | 1:30.00 |
| 6 | 6 | Gilbert NICHOLLS | 9 | Grantham | 1:30.00 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 7 | George PAYNE | 10 | Deepings | 1:30.00 |
| 2 | 9 | Ralph MILNE | 10 | Grantham | 1:30.00 |
| 3 | 13 | Jack DAWSON | 9 | Deepings | 1:30.00 |
| 4 | 14 | Oscar BEMBRIDGE | 9 | Grantham | 1:30.00 |
| 5 | 15 | Ethan DANIELS | 11 | Lincoln Vulc | 1:15.56 |
| 6 | 16 | Jenson FRANCIS-SWABY | 10 | Co Lincoln P | 1:09.82 |
| 7 | 17 | Laurence DE ROSE | 9 | Deepings | 1:09.27 |
| 8 | 20 | Leo GOODWIN | 12 | Lincoln Vulc | 1:02.19 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 21 | Henry BOWERS | 10 | Grantham | 1:01.95 |
| 2 | 22 | Tom GRIFFIN | 11 | Deepings | 1:01.68 |
| 3 | 23 | Hector BARR | 10 | Deepings | 57.57 |
| 4 | 24 | Zachary SMITH GOMEZ | 10 | Lincoln Vulc | 56.00 |
| 5 | 25 | Edward BIRINY | 11 | Lincoln Vulc | 55.73 |
| 6 | 26 | Benjamin BROWN | 10 | Deepings | 54.86 |
| 7 | 27 | Finlay MATHESON | 9 | Co Lincoln P | 54.49 |
| 8 | 28 | Ethan PEART | 10 | Deepings | 54.23 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 29 | Henry LEONARD | 9 | Grantham | 53.63 |
| 2 | 30 | Ethan COOK | 10 | Co Lincoln P | 52.88 |
| 3 | 31 | Charles BLYTH | 11 | Lincoln Vulc | 52.64 |
| 4 | 32 | Leo FRANCZAK | 10 | Co Lincoln P | 52.58 |
| 5 | 33 | Finlay HODSON | 9 | Deepings | 51.66 |
| 6 | 34 | Ethan MEHTA | 11 | Lincoln Vulc | 51.23 |
| 7 | 35 | Lewis CLARKE | 12 | Co Lincoln P | 51.23 |
| 8 | 37 | Alex HUCKLE | 9 | Co Lincoln P | 50.66 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 38 | Jack PAIGE | 11 | Deepings | 50.11 |
| 2 | 39 | Albie WILSON | 9 | Deepings | 49.90 |
| 3 | 41 | Ksawery WRONSKI | 12 | Co Lincoln P | 47.96 |
| 4 | 42 | Charlie ARMSTRONG | 12 | Deepings | 47.74 |
| 5 | 43 | Jack ROWSELL | 11 | Co Lincoln P | 46.81 |
| 6 | 44 | Zac RHOADES | 12 | Co Lincoln P | 45.91 |
| 7 | 45 | Fox RICHARDSON | 9 | Co Lincoln P | 45.80 |
| 8 | 46 | Felix THORNDIKE | 9 | Lincoln Vulc | 45.68 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 47 | Rory MACKFALL | 12 | Lincoln Vulc | 45.09 |
| 2 | 48 | Daniel GODDARD | 11 | Grantham | 44.64 |
| 3 | 49 | Tom BARRATT | 11 | Gainsborough | 44.03 |
| 4 | 51 | Zhengxi (John) GUO | 9 | Grantham | 43.60 |
| 5 | 52 | Louis WRIGHT | 12 | Grantham | 43.48 |
| 6 | 53 | George Arthur PYKE | 12 | Gainsborough | 42.98 |
| 7 | 54 | George DOLAN | 9 | Grantham | 42.67 |
| 8 | 55 | Siddharth SUTHAN | 11 | Co Lincoln P | 41.83 |
| Heat Number - 7 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 57 | Zachary TOMLINSON | 12 | Co Lincoln P | 39.40 |
| 2 | 61 | Derrin BROCKLEBANK | 12 | Grantham | 37.05 |
| 3 | 63 | Henry DOLAN | 12 | Grantham | 35.49 |
| 4 | 65 | Markas PARAPIJONAVICIU | 12 | Grantham | 32.55 |
| 5 | 64 | Toby EDMONDSON | 11 | Grantham | 33.67 |
| 6 | 62 | Freddie HIRST | 11 | Grantham | 36.21 |
| 7 | 59 | Liam EDMEADES | 10 | Deepings | 38.92 |
| 8 | 56 | William PENNOCK | 12 | Grantham | 40.56 |