EVENT 12 Open/Male 09 & Over 100m Butterfly - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 2 | Leo BARNETT | 12 | Grantham | 1:47.53 |
| 4 | 4 | Henry DOLAN | 10 | Grantham | 1:45.00 |
| 5 | 3 | Isacc DONALDSON-BADGER | 11 | Deepings | 1:45.77 |
| 6 | 1 | Freddie HIRST | 9 | Grantham | 1:56.51 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 6 | Jonathan GBYLICZEK | 12 | Co Lincoln P | 1:40.02 |
| 2 | 8 | Eugene CHEU | 12 | Grantham | 1:36.70 |
| 3 | 10 | Ethan DERBY | 13 | Lincoln Vulc | 1:34.17 |
| 4 | 12 | Henry WILLERTON | 10 | Skegness | 1:31.22 |
| 5 | 11 | Oliver CLARKE | 11 | Deepings | 1:31.43 |
| 6 | 9 | Joel SADLER | 13 | Grantham | 1:35.35 |
| 7 | 7 | Callum LOYNES | 12 | Co Lincoln P | 1:40.00 |
| 8 | 5 | Elliot MCWHIRTER | 14 | Lincoln TSA | 1:41.17 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 14 | Ethan HUNTER | 13 | Lincoln Vulc | 1:30.00 |
| 2 | 16 | Samuel NICHOLS | 12 | Grantham | 1:25.07 |
| 3 | 18 | Harry VICKERS | 16 | Lincoln Vulc | 1:15.57 |
| 4 | 20 | Oliver JONES | 15 | Lincoln Vulc | 1:12.74 |
| 5 | 19 | Chris WILLERTON | 39 | Skegness | 1:12.77 |
| 6 | 17 | Stanley THURLOW | 11 | Lincoln Vulc | 1:21.92 |
| 7 | 15 | Oliver WILKINSON | 11 | Lincoln Vulc | 1:26.51 |
| 8 | 13 | Lucas GOODWIN | 13 | Lincoln Vulc | 1:30.00 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 22 | Oliver GARNER | 14 | Co Lincoln P | 1:08.74 |
| 2 | 24 | Lucas NEWBOULT | 14 | Lincoln Vulc | 1:06.27 |
| 3 | 26 | Daniel DEGNAN | 15 | Grantham | 1:05.52 |
| 4 | 28 | Owen HATHWAY | 17 | Grantham | 1:01.96 |
| 5 | 27 | Stuart HAMER | 49 | Co Lincoln P | 1:02.05 |
| 6 | 25 | James NICHOLS | 15 | Grantham | 1:05.68 |
| 7 | 23 | Morgan FARRAR | 14 | Co Lincoln P | 1:06.32 |
| 8 | 21 | Jacob HEGG | 14 | Lincoln Vulc | 1:10.08 |