The building, now converted to a residence and named 'Incline Cottage', stands at the head of the Marchogion railway incline and originated as the incline winding house. The 'railway' dates from 1798 when Benjamin Wyatt built a tramway to carry flint from Porth Penrhyn to a mill at Llandygai to be ground for Staffordshire's pottery industry. Horses pulled waggons along the valley of the Afon Cegin to the foot of the incline, and they were drawn up the incline by chains wound round a vertically mounted drum, probably powered by a horse gin. A further incline lowered the waggons from Llandygai village to the mill. In 1801 the tramway was extended from Llandygai to serve the Penrhyn slate quarries near Bethesda, with two further inclines, and most of the quarries' output travelled this route until 1879 when a new alignment avoiding the inclines came into use. With the majority of load passing downwards, gravity working could be used, using a horizontal winding drum.
The building has an 'H' plan, suggesting that the winding drum was housed in the centre with waggons passing under it. The two side wings are constructed of fine ashlar and have classical proportions. It is thought that the east side was a stable, and the west side was living accommodation.
Some information from CADW Listing.
W J Crompton, RCAHMW, 22 October 2009.