EVENT 303 Men MC 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 2 | James CASH | 10 | Deepings | 6:00.98 |
| 2 | 4 | Daniel HEPPLESTONE | 10 | Lincoln Vulc | 5:54.66 |
| 3 | 6 | William TAYLOR | 08 | Louth | 5:39.36 |
| 4 | 8 | Hayden POTTS | 08 | Lincoln Vulc | 5:32.82 |
| 5 | 7 | Frank LAMB | 09 | South Lincs | 5:34.10 |
| 6 | 5 | James NICHOLS | 09 | Grantham | 5:49.40 |
| 7 | 3 | James THOMAS | 10 | Gainsborough | 5:59.53 |
| 8 | 1 | Charlie BISBY | 11 | South Lincs | 6:10.00 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 10 | Jake ADAMS | 07 | Louth | 5:30.50 |
| 2 | 12 | Matteo MONACO | 09 | South Lincs | 5:27.33 |
| 3 | 14 | Zach HOPKINSON | 09 | Grantham | 5:25.22 |
| 4 | 16 | Kieran NG | 10 | South Lincs | 5:20.39 |
| 5 | 15 | Christian O'MALLEY | 06 | Lincoln Vulc | 5:22.94 |
| 6 | 13 | Jacob BRIERS | 08 | Deepings | 5:25.60 |
| 7 | 11 | Ryan NORTON | 07 | Boston | 5:28.71 |
| 8 | 9 | Leon BAILEY | 06 | Louth | 5:31.53 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 18 | Henry CRUST | 05 | Co Lincoln P | 5:13.88 |
| 2 | 20 | Oliver SORRELL | 07 | South Lincs | 4:56.91 |
| 3 | 22 | Owen HATHWAY | 06 | Grantham | 4:54.70 |
| 4 | 24 | Rico BRINGEMAN | 05 | South Lincs | 4:30.00 |
| 5 | 23 | Alfie BISBY | 07 | South Lincs | 4:48.40 |
| 6 | 21 | Oscar GOLDSMITH | 08 | South Lincs | 4:56.27 |
| 7 | 19 | Finnley DANBY | 06 | Boston | 5:12.20 |
| 8 | 17 | Jacob FISH | 09 | Grantham | 5:18.10 |