While on military service in Ireland, in 1612 Edward Trevor married Rose, a daughter of Henry Ussher, Archbishop of Armagh, and acquired an estate in County Down which was renamed Rostrevor, incorporating his own name.
The pupils come from the surrounding catchment area: Warrenpoint, Annalong, Newcastle, Castlewellan, Hilltown and Rostrevor.
His public buildings include Carlow County Court House (1828),Tralee County Court House, County Kerry (1828) and the Ross Monument, Rostrevor, County Down (1826), commemorating Major-General Robert Ross (1766–1814).
He owns Ballyedmond Castle in Rostrevor, Corby Castle in Cumbria, and No. 9, Belgrave Square, London (a 6-storey townhouse purchased in 2006 for about £12m, restored during the following three years).
Trevor was the son of Sir Edward Trevor of Rostrevor, County Down, and of Brynkinalt Hall, near Chirk in Denbighshire, by his marriage to Rose Ussher, a daughter of Henry Ussher (ca. 1550–1613), Archbishop of Armagh.
In December 1922, the Christian Brothers purchased the Rostrevor Estate at Magill for a sum equivalent to $20,500.