EVENT 505 Open/Male 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 2 | 1 | Oliver Garner | 15 | Co Lincoln P | 5:15.27 |
| 3 | 3 | William Vere | 16 | South Lincs | 5:15.04 |
| 4 | 5 | Flynn Clark | 14 | Derby Excel | 5:12.43 |
| 5 | 4 | Arlo Hems Gillson | 14 | Repton | 5:12.67 |
| 6 | 2 | Daniel Bywater | 16 | Bramcote | 5:15.16 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 7 | Mahrey Caine | 16 | Arnold | 5:10.97 |
| 2 | 9 | Oliver Shepherd | 16 | Deepings | 5:10.37 |
| 3 | 11 | Victor Bramley-Howell | 15 | Co Leicester | 5:08.39 |
| 4 | 13 | Robbie Duff | 14 | Lincoln Vulc | 5:05.70 |
| 5 | 12 | Jack Hicks | 16 | Lincoln Vulc | 5:07.71 |
| 6 | 10 | Theo Black | 15 | Leic Sharks | 5:10.30 |
| 7 | 8 | Peter Nightingale | 15 | Co Leicester | 5:10.94 |
| 8 | 6 | Jacob Harness | 15 | Bassetlaw SS | 5:12.10 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 15 | James Cash | 15 | Deepings | 5:04.71 |
| 2 | 17 | David Bielawski | 16 | Northampton | 5:03.70 |
| 3 | 19 | George Howard | 13 | Co Leicester | 5:03.30 |
| 4 | 21 | Matthew Tompkinson | 16 | Louth | 4:59.19 |
| 5 | 20 | Kais Alhijazi | 14 | Co Leicester | 5:01.68 |
| 6 | 18 | Francesco Monaco | 13 | South Lincs | 5:03.50 |
| 7 | 16 | Oliver Smith | 16 | Radford | 5:04.67 |
| 8 | 14 | Tyler Shaw | 14 | Derby Excel | 5:05.67 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 23 | Lucas Granville | 17 | Repton | 4:57.88 |
| 2 | 25 | Zach Hopkinson | 16 | Grantham | 4:56.10 |
| 3 | 27 | Oliver Dovey | 15 | Corby | 4:54.66 |
| 4 | 29 | Jacson Crabb | 14 | Co Leicester | 4:52.90 |
| 5 | 28 | Jacob Fish | 16 | Grantham | 4:53.86 |
| 6 | 26 | Jacob Briers | 17 | Deepings | 4:55.67 |
| 7 | 24 | Maxwell Burdett | 13 | Co Leicester | 4:57.40 |
| 8 | 22 | Edward Oscroft | 16 | Northampton | 4:58.60 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 31 | Arthur Blacklaws | 15 | Co Leicester | 4:52.24 |
| 2 | 33 | Freddie Burdett | 15 | Co Leicester | 4:47.70 |
| 3 | 35 | Edun Rowe | 17 | Northampton | 4:46.60 |
| 4 | 37 | Carlos Sierra Villegas | 17 | Chesterfield | 4:42.92 |
| 5 | 36 | James Lake | 18 | Loughborough | 4:46.09 |
| 6 | 34 | Harry Lucas | 15 | Co Leicester | 4:46.70 |
| 7 | 32 | Thomas Townsend | 16 | Repton | 4:50.47 |
| 8 | 30 | Joel Harby | 16 | Nova Cent'n | 4:52.40 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 39 | Jack Hurry | 16 | Northampton | 4:41.50 |
| 2 | 41 | Jack Smith | 15 | Co Leicester | 4:39.00 |
| 3 | 43 | Elliot Sibley | 20 | Repton | 4:34.28 |
| 4 | 45 | Thomas Wilkinson | 19 | Lboro Uni | 4:24.39 |
| 5 | 44 | Austyn Manley | 15 | Repton | 4:26.68 |
| 6 | 42 | Jack Bignell | 17 | Northampton | 4:35.54 |
| 7 | 40 | Jacob Pemberton | 16 | Derby Excel | 4:39.30 |
| 8 | 38 | Niklas Saukko-Paavola | 17 | Leic Sharks | 4:42.36 |