Castell Deudraeth is named after the twelfth century castle which stood to the southwest of the current mansion house, which is of eighteenth century origin. David Williams MP bought the house, then called Bron Eryri, in 1841 and extensively remodelled and expandedit before renaming it. It was intended to be part of the nearby Portmeirion village, offering further accommodation to guests, but this plan was not brought to fruition until 2001.

The house is of local slatestone construction with dressed slatestone and yellow sandstone dressings, topped by crenallated and corbelled parapets and slate roofs. It comprises a three-bay, four-storey central block, with an adjoining keep-like block to the left and square tower to the right. The building is entered via a segmentally-arched entrance below a projecting single storey porch. There are sandstone cross-windows throughout, with two-light windows to the second floor of the central section and slit-lights to the octagonal tower which forms part of the keep-block; label-course to the second floor of the southeast block. There is a modern single-storey conservatory addition to the rear of the property.

Source: Cadw Listed Building Record

K Steele, RCAHMW, 9 February 2009