Schools
O
| Name | Category | Notes |
|---|---|---|
| Oakbank School | Comprehensive | Keighley. |
| Oakham | Public | |
| Oaklands Roman Catholic Comprehensive School | Comprehensive | Waterlooville. |
| O'Connell Christian Brothers School | Other private | Dublin. |
| Ogwen Grammar School | Grammar | |
| Old College | Homerton. Dissenting ministry. | |
| Old Cumnack Parish School | Elementary | Ayrshire. |
| Old Hall Green School | Other private | Hertfordshire. |
| Oldham High School | Grammar | |
| Oldmeldrum Public School | Elementary | Not a 'public school' in the Headmasters' Conference sense. |
| Old Moat Primary School | Primary | Manchester. |
| Old Palace School | Independent | Croydon. |
| Old Presbyterian College | Other private | Belfast. |
| Old Swinford Hospital School | State boarding | |
| Olivers Mt School | Other private | Scarborough. |
| Omagh Academy | Grammar | Omagh. |
| Oratory School, Edgbaston | Public | |
| Oratory School, Woodcote | Other private | |
| Orient College | Unknown | Skegness. |
| Orme Girls' School | Unknown | Newcastle-under-Lyme. |