At its height in the 16th century, the mansion, entered by two drawbridges over a moat, comprised a great hall and a number of secondary structures.

Subsequently in the ownership of the Powells, and then the Lorimers, the house became a centre of Catholic recusancy following the English Reformation.

The American journalist and diplomat Wirt Sikes, United States consul at Cardiff in the 1870s and 1880s, recorded an encounter between Wern-ddu's last hereditary owner, Roger ap Probert, and a stranger, in his Rambles and Studies in Old South Wales, published in 1881.

[3] Sir Joseph Bradney, in his multi-volume work on the county, A History of Monmouthshire from the Coming of the Normans into Wales down to the Present Time, suggests that Perth-hir was bought from the de Clares in the 14th century by Thomas ap Thomas, fourth son of Gwilym ap Jenkin.

[10] Their home became a refuge for Catholic priests and services were held in a small chapel, dedicated to St Catherine,[11] which existed until the mid-18th century.

[12] The most notable priest in residence was Matthew Pritchard (or Prichard) (1669-1750), Catholic bishop and Vicar Apostolic of the Western District for much of the first half of the 18th century.

[23] Elisabeth Whittle, in her Glamorgan and Gwent volume of the Ancient and Historic Wales series of guides published in 1992, notes the large ditch to the north and east of the house.

[22][e][f] Fox and Raglan note the window's "ogee arch", a popular style in Monmouthshire at that date.