EVENT 504 Girls 12 Yrs/Over 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 3 | 1 | Edie Hawtin | 12 | Tring | 6:42.67 |
| 4 | 3 | Aine Dunwoodie | 12 | Co St Albans | 6:19.41 |
| 5 | 2 | Chloe Coster | 12 | Hatfield | 6:32.51 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 4 | Amy Harper | 12 | Watford SC | 6:16.46 |
| 2 | 6 | Megan Worley | 13 | Watford SC | 6:10.15 |
| 3 | 8 | Olivia Riley | 13 | Hatfield | 6:09.02 |
| 4 | 10 | Holly Morgan | 13 | Hoddesdon | 6:04.54 |
| 5 | 9 | Thea Patel | 12 | Potters Bar | 6:08.69 |
| 6 | 7 | Jessica Warne | 14 | Watford SC | 6:09.28 |
| 7 | 5 | Alexandra Braniff | 13 | Watford SC | 6:12.27 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 12 | Tamsin Moren | 14 | Berkhamsted | 6:01.66 |
| 2 | 14 | Florence Crowley | 13 | Harpenden | 5:59.84 |
| 3 | 16 | Amy Boreham | 13 | Watford SC | 5:57.88 |
| 4 | 18 | Isabel Chaplin | 14 | Co St Albans | 5:56.84 |
| 5 | 17 | Charlotte Williams | 13 | Cheshunt | 5:57.00 |
| 6 | 15 | Catherine Ryan | 15 | Hoddesdon | 5:59.81 |
| 7 | 13 | Niamh O'Meara | 13 | Watford SC | 6:01.58 |
| 8 | 11 | Olivia Kavanagh | 14 | Potters Bar | 6:03.46 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 20 | Lucinda Stanley | 15 | Harpenden | 5:54.89 |
| 2 | 22 | Grace Cawley | 13 | Hemel Hemp | 5:53.92 |
| 3 | 24 | Abigail Rock | 17 | Potters Bar | 5:52.81 |
| 4 | 26 | Caitlin Hartley | 15 | Hatfield | 5:50.00 |
| 5 | 25 | Rosie Cave | 16 | Tring | 5:52.14 |
| 6 | 23 | Kirsty Fuge | 13 | Hatfield | 5:53.50 |
| 7 | 21 | Evie Brown | 14 | Watford SC | 5:54.69 |
| 8 | 19 | Jemima Samols | 15 | Co St Albans | 5:55.06 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 28 | Jessie Bird | 16 | Stevenage | 5:49.13 |
| 2 | 30 | Freya Beresford | 15 | Hemel Hemp | 5:44.64 |
| 3 | 32 | Katy Lane | 13 | Co St Albans | 5:43.58 |
| 4 | 34 | Sofia Peccei | 14 | Watford SC | 5:41.70 |
| 5 | 33 | Bella Parkus | 14 | Hoddesdon | 5:42.55 |
| 6 | 31 | Emilia Dunwoodie | 14 | Co St Albans | 5:44.19 |
| 7 | 29 | Lucy Coia-Bell | 14 | Co St Albans | 5:48.37 |
| 8 | 27 | Katie Jeffrey | 15 | Hatfield | 5:49.59 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 36 | Helen Stafford | 15 | Co St Albans | 5:38.44 |
| 2 | 38 | Kiera Beaver | 15 | Watford SC | 5:34.35 |
| 3 | 40 | Isabella Chapman | 15 | Harpenden | 5:33.88 |
| 4 | 42 | Georgia Pritchard | 14 | Hatfield | 5:30.94 |
| 5 | 41 | Ella Murphy | 17 | Harpenden | 5:31.01 |
| 6 | 39 | Eleanor Craig | 15 | Watford SC | 5:34.28 |
| 7 | 37 | Alice Richardson | 16 | Co St Albans | 5:36.06 |
| 8 | 35 | Lucy Jordan-Caws | 16 | Hatfield | 5:39.23 |
| Heat Number - 7 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 44 | Olivia Seal | 17 | Hatfield | 5:29.81 |
| 2 | 46 | Isabelle Soulsby | 16 | Berkhamsted | 5:26.19 |
| 3 | 48 | Daisy Sandon | 16 | Stevenage | 5:24.79 |
| 4 | 50 | Erin O'Meara | 16 | Watford SC | 4:59.90 |
| 5 | 49 | Valeria Giron | 14 | Hatfield | 5:20.65 |
| 6 | 47 | Anastasia Wilkinson | 14 | Hatfield | 5:25.76 |
| 7 | 45 | Nellie Eastland | 17 | Bishop Stort | 5:27.05 |
| 8 | 43 | Jessica Heesom | 16 | Potters Bar | 5:30.93 |