Commentary on Sections Schedule 11: Schools: exceptions Effect
863.This paragraph provides that a mixed-sex school some of whose pupils are boarders may lawfully admit only pupils of one sex to be boarders. The exception applies even if some members of the other sex are admitted as boarders, so long as their numbers are comparatively small. It allows a school to refuse to admit a pupil to a boarding place at the time he or she initially joins the school, or to provide him or her with boarding facilities at a later stage.