EVENT 123 Boys 16/17 Yrs 100m Breaststroke - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 0 | 2 | Thomas Arkle | 16 | Cheshire | 1:09.23 |
| 1 | 4 | Hiroki Harazawa | 17 | Surrey | 1:08.55 |
| 2 | 6 | Benjamin Stuckey | 17 | Essex | 1:08.13 |
| 3 | 8 | Daniel Timms | 17 | Notts | 1:07.80 |
| 4 | 10 | Lucas Navarro | 17 | Middlesex | 1:07.40 |
| 5 | 9 | Kyle Borley | 17 | N & Durham | 1:07.60 |
| 6 | 7 | Noah Vides | 16 | Dorset | 1:07.81 |
| 7 | 5 | Max Elphick | 16 | Berks&SBucks | 1:08.22 |
| 8 | 3 | Chris Smith | 16 | Herts | 1:08.80 |
| 9 | 1 | Christopher Yule | 16 | Scot North | 1:09.44 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 0 | 12 | Max Hewett | 17 | Hampshire | 1:06.99 |
| 1 | 14 | Jack Smith | 17 | Lancashire | 1:06.20 |
| 2 | 16 | Joseph Faulkner | 17 | Yorkshire | 1:05.77 |
| 3 | 18 | Daniel Lim | 16 | Scot East | 1:04.69 |
| 4 | 20 | Adam Peaty | 17 | Derbyshire | 1:00.30 |
| 5 | 19 | Alex Murphy | 17 | Ox & N Bucks | 1:02.56 |
| 6 | 17 | James Guy | 16 | Somerset | 1:05.77 |
| 7 | 15 | Rory Shirley | 17 | Scot West | 1:05.83 |
| 8 | 13 | James Robinson | 17 | Staffs | 1:06.63 |
| 9 | 11 | Patrick Ham | 17 | Kent | 1:07.33 |