The School On Cloud Ridge — Mabel Esther Allan

When Pussy and Collie Alleyne go to a co-educational boarding school in the Cotswolds, the other fifty or so boys and girls are new too, for it is the school's first term. Pussy is thrilled when she is elected to the first School Council, but she soon realizes that it is going to be a difficult position, especially as she and the unfriendly and sophisticated Helen cannot get on. But, she make friends with the three Kavanaghs from Ireland, with Myra Drury from Lancashire, and with a boy called Hugo, who is instrumental in starting them off on a very original treasure hunt...