1640 and later, rough hewn stone, 1 storey and attics; label on window, originally round headed entrance, stone gabled ends.

[Additional:]

Dyffryn-gwyn (Hen Dyfryn Gwyn) is an impressive house of developed Snowdonian plan-type with good timber detail and a characteristic principal doorway with a head of voussoirs. The unusually wide entrance passage flanked by moulded post-and-panel partitions is explained by the former accommodation of a service-room at the end of the passage. As originally planned Dyffryn-gwyn had a passage and service-room between hall (with fireplace stair) and outer parlour. The service-room was lit by a window where one would expect a cross-passage doorway. The reed-moulding of the partitions is repeated in the ceiling on the joists, and plan and timber detail belong to the original building phase. The first floor was divided into two chambers by a post-and-panel partition with a doorway with double ogee door-head. These chambers were lit by hipped dormers. A date inscription on the prominent three-light ovolo hall window reads 1640. Tree-ring dating now shows that the collar-beam trusses are somewhat earlier. It seems therefore the house was built in the earlier C17th but refitted with fashionable ovolo windows (and no doubt with other improvements) in 1640. A further inscription of 1772 dates a phase of modernisation, which probably included the insertion of a stair in the passage, superseding the hall fireplace stair, and the construction of the rear detached kitchen/bake-house. Description and plans in the NMRW. R.F. Suggett/RCAHMW/March 2016.