EVENT 201 Men 17 Yrs/Over 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 2 | Luke Clegg | 05 | Bo Kirklees | 4:19.10 |
| 2 | 4 | B Howarth-Osborne | 04 | Co Sheffield | 4:06.24 |
| 3 | 6 | Finn Drysdale | 05 | Royal Wolv | 4:06.82 |
| 4 | 8 | Razvan Grumazescu | 04 | Northampton | 4:08.77 |
| 5 | 7 | Thomas Deffains | 04 | Mt Kelly | 4:15.28 |
| 6 | 5 | Adam Tabernacle | 04 | Preston | 4:19.02 |
| 7 | 3 | Joseph Stout | 05 | Co Salford | 4:08.53 |
| 8 | 1 | Kaiden Welsby | 05 | Stockport Mo | 4:15.89 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 0 | 10 | Sam Williamson | 04 | Mt Kelly | 4:14.09 |
| 1 | 12 | Jack Booth Rudd | 04 | Maidenhead | 4:10.50 |
| 2 | 14 | Max Geysen-Holley | 05 | Co Cardiff | 4:08.99 |
| 3 | 16 | Nathan Potter | 05 | Maidenhead | 4:14.50 |
| 4 | 18 | Donatas Dragasius | 04 | Mt Kelly | 4:12.17 |
| 5 | 17 | Joseph Bartley | 04 | Sutton Cheam | 4:03.46 |
| 6 | 15 | Luca Staines | 04 | Wycombe Dist | 4:16.09 |
| 7 | 13 | Luke Critchlow | 05 | Stockport Mo | 4:13.61 |
| 8 | 11 | Luke Booth | 05 | Rotherham Mo | 4:11.16 |
| 9 | 9 | Daniel Cox | 04 | Wycombe Dist | 4:12.62 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 0 | 20 | Alexander Harrand | 05 | Derventio | 4:12.72 |
| 1 | 22 | Arthur Logan | 04 | Crawley | 4:05.46 |
| 2 | 24 | James Shevchenko | 05 | Royal Wolv | 4:05.44 |
| 3 | 26 | Cameron Carlos | 05 | Barnet Copt | 4:11.16 |
| 4 | 28 | Solomon Williams | 05 | Millfield | 4:05.02 |
| 5 | 27 | Noah Jameson Neal | 04 | Plymouth Lea | 4:12.13 |
| 6 | 25 | Ben Shelton | 04 | Co Leeds | 4:13.34 |
| 7 | 23 | Oliver Burns | 05 | Royal Wolv | 4:11.96 |
| 8 | 21 | Patrick Braddock | 04 | Oldham Aqua | 4:14.18 |
| 9 | 19 | Charles Crewe | 04 | RTW Monson | 4:16.97 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 0 | 30 | Alexander Volkovoy | 05 | Co Salford | 4:08.20 |
| 1 | 32 | Ben Merriman | 05 | Torfaen D | 4:07.28 |
| 2 | 34 | Elijah Kendrick | 04 | Plymouth Lea | 4:07.12 |
| 3 | 36 | Christian Duetoft | 05 | Guildford Ct | 4:08.56 |
| 4 | 38 | Adam Hall | 01 | Loughboro Un | 4:07.28 |
| 5 | 37 | Alexander Sargeant | 02 | Millfield | 4:01.30 |
| 6 | 35 | Cameron Travis | 04 | Aberdeen Per | 4:01.20 |
| 7 | 33 | Elliot Sibley | 05 | Nova Cent'n | 4:12.18 |
| 8 | 31 | Henry Maw | 04 | Southport | 4:09.52 |
| 9 | 29 | Sean McCann | 05 | Co Leicester | 4:05.55 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 0 | 40 | Josh Williams | 02 | Swansea Uni | 4:02.86 |
| 1 | 42 | Ethan Rayment | 01 | Plymouth Lea | 4:06.74 |
| 2 | 44 | Wyatt Walsh | 03 | Millfield | 4:04.81 |
| 3 | 46 | Michael James Flynn | 03 | Co Glasgow | 4:04.08 |
| 4 | 48 | Jack Fleming | 01 | Loughboro Un | 4:12.35 |
| 5 | 47 | Joshua Weston | 04 | Wycombe Dist | 4:10.45 |
| 6 | 45 | Angus Allison | 03 | UniOfStirl | 4:03.04 |
| 7 | 43 | Jackson O'Rourke | 02 | Northampton | 4:05.04 |
| 8 | 41 | Max Adams | 04 | Co Salford | 4:08.57 |
| 9 | 39 | Nathan Wells | 98 | West Norfolk | 4:08.34 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 0 | 51 | Pierce Greening | 03 | UniOfStirl | 4:06.98 |
| 1 | 55 | Reece Grady | 05 | Stockport Mo | 4:00.88 |
| 2 | 59 | Nathan Hughes | 00 | Swansea Uni | DN:C . |
| 3 | 63 | George Barber | 01 | Co Sheffield | 3:58.92 |
| 4 | 67 | William Bell | 02 | Loughboro Un | 3:58.03 |
| 5 | 65 | R Rowbotham-Keating | 05 | Co Manch Aq | 3:58.98 |
| 6 | 61 | Ben Cope | 01 | Co Sheffield | 3:59.03 |
| 7 | 57 | Joshua O Brien | 05 | Co Cardiff | 4:01.88 |
| 8 | 53 | Samuel Tucker | 04 | Wycombe Dist | 4:10.96 |
| 9 | 49 | Joel Thompson | 01 | Shiverers | 4:05.55 |
| Heat Number - 7 |
| Lane | Comp.No. | Name | YoB | Club | Time |
| 0 | 52 | Harry Wynne-Jones | 05 | Co Milton K | 4:01.65 |
| 1 | 56 | Reuben Visda | 03 | Co Sheffield | 4:01.35 |
| 2 | 60 | Matthew Woodhall | 04 | Co Sheffield | 4:04.92 |
| 3 | 64 | Joseph Deighan | 03 | Swansea Uni | 4:01.48 |
| 4 | 68 | Jakob Goodman | 00 | Loughboro Un | 3:55.67 |
| 5 | 66 | Tyler Melbourne-Smith | 05 | Co Liverpool | 3:55.74 |
| 6 | 62 | Thomas Trebilcock | 03 | Plymouth Lea | 4:00.47 |
| 7 | 58 | Jack Muncey | 03 | UniOfStirl | 4:04.17 |
| 8 | 54 | Tony Joe Trett Oliver | 99 | UniOfStirl | 4:02.12 |
| 9 | 50 | Joe Cooper | 04 | teamipswich | 4:06.55 |