Complex sentence: Ashmead, Chandos and Westal are the girls' boarding houses whilst the boys reside in either Boyne House, Christowe, Hazelwell, Leconfield or Newick House.
Split into simpler sentences: Ashmead, Chandos and Westal are the girls' boarding houses. The boys reside in Boyne House, Christowe, Hazelwell, Leconfield, and Newick House.