Complex sentence: It was announced on 7 May 2014 that Percy would become the 45th Dean of Christ Church in Oxford--making him (currently) the youngest Head of House in Oxford (excluding heads of Permanent Private Halls and graduate colleges).
Split into simpler sentences: It was announced on 7 May 2014 that Percy would become the 45th Dean of Christ Church in Oxford. This made him (currently) the youngest Head of House in Oxford (excluding heads of Permanent Private Halls and graduate colleges).