Dyffryn House (nprn 18592) is a large mansion in French Renaissance and English Baroque styles situated in gently rolling countryside approximately 2km south of the village of St Nicholas in the Vale of Glamorgan. Although a park and gardens have existed around Dyffryn House since at least the eighteenth century, the site is best known for its Edwardian gardens, considered to be the grandest and most outstanding example in Wales (307771). 

The earliest record of a park at Dyffryn is the Ordnance Surveyor's drawing of 1811. The 1878 first edition Ordnance Survey map shows a small park to the north and south of the house, with a lodge at the north end and a long drive leading southwards through the park to the house. A further drive approaches from a lodge to the east (east Lodge. Both lodges survive, North Lodge and East Lodge.
The park was laid out with single trees, clumps, and old hedge-line trees. John Cory bought the 2000-acre estate in 1891 and made some changes to the park before 1900, notably by taking in a field in the north-west corner, extending the garden southwards to make a tennis lawn and making an informal lake at the south end of the park. The park was reduced to a much smaller area by the creation of the gardens from 1905 onwards. These took up the whole of the park to the south of the house and the area between the house and the river Waycock to the north. Just north of the river aerial survey has revealed wahta appear to be garden features (415558).

Sources:
Cadw 2000: Register of Parks and Gardens of Special Historic Interest in Wales, Glamorgan (ref: PGW(Gm)32(GLA)).
Ordnance Survey first-edition six-inch map, sheet: Glamorgan XLVI.11 (1885).
Ordnance Survey first-edition six-inch map, sheet: Glamorgan XLVI.11 (1901).  

RCAHMW, 15 July 2022