EVENT 504 Mixed 1500m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 2 | David KANDELAKI | 13 | Linslade | |
| 2 | 4 | Leo DOWDEN | 15 | Leighton Buz | |
| 3 | 6 | Marcus XU | 13 | Linslade | |
| 4 | 8 | Cora PAYNE | 10 | Bletchley | |
| 5 | 7 | Megan MCKAY | 15 | Leighton Buz | |
| 6 | 5 | Filip BOCHENKO | 12 | Ealing | |
| 7 | 3 | Eleanor WAHL | 11 | Leighton Buz | |
| 8 | 1 | Josephine BROWN | 11 | Linslade | |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 10 | Cameron THACKRAH | 12 | Linslade | |
| 2 | 12 | Yuma HAVERLY | 12 | Ealing | |
| 3 | 14 | Sebastian MCCUSKER | 13 | Leighton Buz | |
| 4 | 15 | Henry CHALONER | 13 | Biggleswade | 24:42.57 |
| 5 | 33 | Matthew HORTON | 15 | Dunstable | 25:00.00 |
| 6 | 13 | Hayden JOHNSON | 15 | Biggleswade | |
| 7 | 11 | Chloe BUCKTROUT | 11 | Linslade | |
| 8 | 9 | Maximos RYAN | 12 | Ealing | |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 17 | Chloe MATTHEWS | 13 | Linslade | 23:06.00 |
| 2 | 19 | Adam MESSIS | 13 | Ealing | 21:58.03 |
| 3 | 22 | Elissa NEO | 12 | Linslade | 21:16.69 |
| 4 | 24 | Joseph FINNERTY | 17 | Linslade | 20:48.20 |
| 5 | 23 | Libby FLITTON | 12 | Dunstable | 20:56.70 |
| 6 | 21 | Ben GORING-FARROW | 14 | Linslade | 21:25.61 |
| 7 | 18 | Cassie BONNER | 10 | Epping For't | 23:00.00 |
| 8 | 16 | Jack MAY | 13 | Linslade | 24:27.60 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 26 | Elizabeth GORE | 13 | Epping For't | 20:28.07 |
| 2 | 28 | Connie FLITTON | 14 | Dunstable | 19:46.30 |
| 3 | 30 | George ADAMSON | 14 | Boldmere | 19:35.70 |
| 4 | 32 | Reece BARCLAY | 34 | Epping For't | 17:23.96 |
| 5 | 34 | Lucy CHARLES-BARCLAY | 31 | Epping For't | 18:08.50 |
| 6 | 29 | Aaron RAWNSLEY | 13 | Harpenden | 19:39.62 |
| 7 | 27 | Jack CANHAM | 13 | Team Luton | 19:47.70 |
| 8 | 25 | Amy EDWARDS | 14 | Boldmere | 20:39.90 |