| Mark Aldwinckle | 1:36.71 | 1996-03-16 | aged 10 | Age Groups |
| Mark Aldwinckle | 1:34.87 | 1996-06-09 | aged 10 | Club championships |
| Mark Aldwinckle | 1:33.52 | 1997-03-01 | aged 11 | Age Groups |
| Mark Aldwinckle | 1:31.78 | 1997-06-22 | aged 11 | Club championships |
| Mark Aldwinckle | 1:30.81 | 1998-03-07 | aged 12 | Herts Major League |
| Mark Aldwinckle | 1:28.19 | 1998-03-14 | aged 12 | Herts Age Groups |
| Thomas Moore | 1:27.25 | 1999-06-26 | aged 12 | Biggleswade Gala |
| Thomas Moore | 1:26.38 | 1999-09-25 | aged 12 | Harlow Open |
| Ian Shannon | 1:24.67 | 2000-04-15 | aged 12 | Herts Age Groups session 8 |
| Jake Robinson | 1:23.68 | 2006-10-07 | aged 12 | Cheshunt Open |
| Jake Robinson | 1:23.53 | 2006-11-11 | aged 12 | Speedo League 2 |
| Jake Robinson | 1:22.53 | 2007-02-03 | aged 12 | Herts Major League 2 |
| Jake Robinson | 1:22.33 | 2007-06-24 | aged 12 | Killerwhales Summer Invitation |