The Gnoll was located on a prominent, steep-sided hill or knoll, on the east side of Neath. 

It is notable for the survival of its largely eighteenth-century landscape park, which is of great historic interest, in its original rural setting above Neath. It lies on the flank of the Vale of Neath, long famed for its picturesque beauty. The landscape is exceptional for its combination of industrial and ornamental functions and for its strong visual relationship with the surrounding countryside. The eighteenth-century landscaping is of several phases, including an exceptionally interesting early transitional layout by Thomas Greening, in the style of designer Stephen Switzer, with formal and informal elements, including a (restored) formal cascade. The following phases include an outstanding informal cascade of the 1740s and the later eighteenth-century follies of a rock-hewn grotto and the Ivy Tower, which forms a prominent landmark in the Neath valley. Although the park’s historic character has been diluted through the loss of the house and forestry planting, most of its structural elements remain intact or have been restored or rebuilt. Most of the major developments in the park and grounds took place during the eighteenth century under the ownership of the Mackworth family.

The park lies on elevated, rolling ground on the south flank of the Vale of Neath. It is linear and orientated north-east by south-west. Its eastern, upper side is largely wooded, its western side more open. On the east the ground rises towards the high ground of Cefn Morfydd, while to the south and west it drops below the park to the town of Neath. The house was sited on a prominent hill at the south-western end of the park (nprn 18814). There are three ponds and a late nineteenth-century reservoir, to supply water for coal mining and copper smelting, and also for ornament.

South of the house site, at the south end of the park, is the wooded Preswylfa valley, largely deciduous, with the Great Pond half way along it. To the north is an open area of parkland, the largest pond, the Fishpond, and a smaller pond with two small islands. Fishpond Wood is mature woodland containing the (restored) formal cascade to the east and remnants of a more extensive lime avenue. This is aligned on a long formal axis from the north end of the hill on which the house stood, across the boundary ha-ha and up the cascade to Brynau Wood and Cefn Morfydd, beyond the park.

The northern part of the park comprises open ground on the western side, now partly a golf course, and Mosshouse Wood, mixed woodland which extends from Fishpond Wood on the south to high ground on the north. It contains the reservoir and a long, informal cascade. There are also several eighteenth-century follies including the rediscovered grotto next to the cascade. To the north-west, above Dan-y-lan farm, is the Ivy Tower (19088), a prominent eighteenth-century eye-catcher folly tower situated on a hilltop to the north of Mosshouse Wood, overlooking the park and the Vale of Neath.

There have been several entrances at The Gnoll, only two of which remain in use. An entrance with imposing castellated stone archway and a simple iron gate now lies on Gnoll Avenue. Inside the entrance the former drive, now a public road, is lined with pines, leading to the War Memorial Gate of Honour entrance (32843). Inside, a tarmac drive runs eastwards up the Preswylfa valley. A former entrance at the end of Gnoll Avenue, to the north-west of the war memorial, is marked by a gate & lodges (18815). 
Gardens and grounds, including walled gardens, lie to the south and east of the house site. (265660; 700035)

Source: Cadw Historic Assets Database (ref: PGW(Gm)50(NEP)).

RCAHMW, 15 February 2022