| B Final | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 1 | Jack ANDREW | 15 | teamipswich | 56.91 |
| 2 | 2 | Harry ROBINSON | 15 | Co Cambridge | 56.50 |
| 3 | 3 | Sonny TRIGG | 17 | teamipswich | 56.07 |
| 4 | 4 | William KEARSEY | 16 | Hatfield | 55.62 |
| 5 | 5 | Joshua DUGGAN | 17 | Hatfield | 56.05 |
| 6 | 6 | Benjamin WHITBOURN | 16 | Dereham | 57.11 |
| 7 | 7 | Oliver MALTBY | 16 | Modernians | 56.86 |
| 8 | 8 | Jordan MANN | 15 | UEA Norwich | 57.05 |