Jenkinson wanted to change the ethos of the School and thought that a "House" system, like the ones used by the best boarding schools, would help. Indeed, the former pupil of Dulwich College, which had a long established House system, had a great supporter on the governors in Sir Arthur Quiller-Couch, an old boy of Clifton College, another school with "Houses".
With fewer than 150 pupils on roll, two Houses were thought sufficient, named after two local manors, Tewington and Treverbyn. By the autumn of 1916, the school had grown to such an extent to warrant a third House, Trenance. Tregrehan was not introduced until 1950.