Penrallt-dafn farm is situated approximately three quarters of a mile west of the small village of Hermon. According to heritage consultancy Trysor, '"Penalltafan" is shown on the Ordnance Survey's Original Surveyors Drawings Newcastle Emlyn map sheet, surveyed in 1811. This was the first detailed map of the whole country and shows that a collection of buildings was already in position now occupied by the modern farmyard. This early survey did not map field boundaries with accurate detail, but the map shows that a large area of the higher ground to the north of the farm buildings was still unenclosed moorland in 1811. Enclosed fields were found along the slopes to the east, west and south of the farm. A group of three cottages some 600 metres to the east-northeast of the farmyard are also shown on this map and labelled as "Penralltafan." The significance of the "Penralltafan" annotation for these cottages is unclear.'
'When the Ordnance Survey published their 1 inch to 1 mile scale First Series map for the area in 1831, based on the 1811 survey, essentially the same picture is presented. Only two of the three cottages recorded to the east-northeast in 1811 are still shown. It is also apparent from this map that there was a division of the farmyard at "Pen-allt Dafn," with two groups of buildings apparent, one to the west and one to the east.'
'The fist detailed map of Penrallt Dafn farm and its field system is the Cynwyl Elfed parish tithe map of 1840. This shows that the farm was a little over 223 acres in area. The field system on the farm is focused on the south facing slopes of the hill, with a large unenclosed parcel of land forming the northern half of the property. Few of the early field parcels can be compared with the modern field system. At this time the tenant was David Davies and the owner Thomas Lloyd. No field names were recorded on the schedule which accompanies the map. One interesting aspect of this map is that it appears to explain the division of the farmyard buildings into two discrete groups on the 1831 Ordnance Survey map. The eastern group formed the core of a smaller, separate farmstead known as Clynmaenllwyd.'
'The detail of the farmyard layout on the tithe map compares to a large extent with the layout shown on the 1889 and 1906 1:2500 scale Ordnance Survey maps. These both show two separate dwellings with associated farm buildings at Penrallt Dafn and Clynmaenllwyd.'
'As recently as the 1964 1:10000 Ordnance Survey map, two farmsteads are shown here. By the time of the 1978 1:2500 scale map however, only Penrallt Dafn survived, with the dwelling in its original position to the west of the farmyard complex. This map shows that the house and farm buildings at Clynmaenllwyd had been replaced by a range of large, modern agricultural buildings serving Penrallt Dafn. This remains the layout of the farm in 2014.
Source: Trysor report entitled 'Penrallt Dafn, Cynwyl Elfed Carmarthenshire Historic Environment Appraisal' by Jenny Hall and Paul Sambrook, published May 2014
M. Ryder, RCAHMW, 6th March 2014