| Extras |
| 60 | Marlborough Blues v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1989 |
| 47 | Old Merchant Taylors v Harrow Wanderers | Merchant Taylors' School Ground, Northwood | 2018 |
| 46 | Repton Pilgrims v Harrow Wanderers | Repton School Ground, Repton | 2001 |
| 42 | Repton Pilgrims v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2005 |
| 41 | Old Westminsters v Harrow Wanderers | Vincent Square, Westminster | 2008 |
| 38 | Old Malvernians v Harrow Wanderers | Malvern College Ground, Malvern | 1982 |
| 37 | Haileybury Hermits v Harrow Wanderers | Haileybury College Ground, Hertford | 1991 |
| 36 | Repton Pilgrims v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2004 |
| 36 | Old Cliftonians v Harrow Wanderers | Clifton College Close Ground, Clifton | 2014 |
| 35 | Shrewsbury Saracens v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1993 |
| 33 | Old Tonbridgians v Harrow Wanderers | Tonbridge School Ground, Tonbridge | 2024 |
| 32 | Old Merchant Taylors v Harrow Wanderers | Durrants Sports Ground, Croxley Green | 1983 |
| 31 | Old Cholmeleians v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1982 |
| 29 | Charterhouse Friars v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2009 |
| 28 | Oundle Rovers v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1991 |
| 28 | Oundle Rovers v Harrow Wanderers | Oundle School Ground, Oundle | 1999 |
| 28 | Old Malvernians v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2010 |
| 27 | Old Cholmeleians v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1992 |
| 27 | Sherborne Pilgrims v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2002 |
| 27 | Felsted Robins v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2005 |
| 26 | Old Cholmeleians v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 2021 |
| 25 | Stowe Templars v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1994 |
| 25 | Old Cliftonians v Harrow Wanderers | Clifton College Close Ground, Clifton | 1994 |
| 25 | Bradfield Waifs v Harrow Wanderers | Bradfield College, Reading | 1996 |
| 25 | Shrewsbury Saracens v Harrow Wanderers | Harrow School Cricket Ground, Harrow-on-the-Hill | 1997 |
| 25 | Repton Pilgrims v Harrow Wanderers | Repton School Ground, Repton | 2003 |
| 25 | Old Malvernians v Harrow Wanderers | North End Lane, Malvern | 2021 |
| 24 | Old Tonbridgians v Harrow Wanderers | Tonbridge School Ground, Tonbridge | 1984 |
| 24 | St Edward's Martyrs v Harrow Wanderers | St Edward's School Ground, Oxford | 2013 |
| 24 | Old Alleynians v Harrow Wanderers | Dulwich College Ground, Dulwich | 2022 |
| 24 | Downside Wanderers v Harrow Wanderers | Downside School, Stratton-on-the-Fosse | 2024 |
