Prehen HousePrehen House is a privately owned 18th century Irish Georgian house on the outskirts of the city of Londonderry. It is thought to have been designed by local architect Michael Priestley and it was built circa 1740 for Andrew Knox, MP for Donegal, after he married Prehen heiress Honoria Tomkins some two years earlier. Andrew Knox's family owned the house for 170 years. After being seized by the Government after the 1914-18 war, Prehen House was brought back into another branch of the Knox family. Prehen is a Grade A listed building.