split between a boys' school and girls' school which was federated, allowing joint staffing/teaching across the two schools whilst the pupils of each school (in years 7 to 11 but not the sixth form) remained separate.
Division into a boys' school and a girls' school that was federated, enabling shared staff and teaching between them, but keeping students from each school (in years 7 to 11) separate, with no overlap for sixth-formers.