History in Structure

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The Old Mill

A Grade II Listed Building in Gelligaer, Caerphilly

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Latitude: 51.6286 / 51°37'42"N

Longitude: -3.2356 / 3°14'8"W

OS Eastings: 314569

OS Northings: 192922

OS Grid: ST145929

Mapcode National: GBR HV.8QTD

Mapcode Global: VH6DL.VBTC

Entry Name: The Old Mill

Listing Date: 18 July 2001

Last Amended: 18 July 2001

Grade: II

Source: Cadw

Source ID: 25531

Building Class: Commercial

Location: Set slightly back from the main thoroughfare and on the opposite side of Nant Llanbradach from the Forge.

County: Caerphilly

Community: Gelligaer

Community: Gelligaer

Locality: Ystrad Mynach

Traditional County: Glamorgan

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There is a possible reference to this mill in C17 but first direct evidence is Emanuel Bowen's map of 1729 where it appears as Llanbradock Mill; appears also on other C18 maps including two recording Llanbradach demesne, in the later of which (1792) a kiln is also shown. Originally a single range aligned roughly E/W, and shown as such on C18 estate maps, it appears L-shaped on Llanfabon Tithe Map of 1842, which also shows 45 acres (18.2 hectares) were farmed with the mill at that time. Dingle containing the mill stream and ascending to Llanbradach Fawr was known then as Cwm y Felin. Census returns of 1841 refer to Ystrad Mill. It was working until 1880s but went out of use by the turn of the century. Some renovation work was carried out in 1923 and maintenance has been continued. Behind the mill the associated earthworks survive including the mill pond and the leat, which passes in a culvert under the road, also under the railway embankment higher up. The wheel pit is unaltered and the tail race enters a culvert passing under the main road and disgorging into Rhymney River. Reputedly there are some signs of an earlier arrangement of the wheel here.

The water wheel was of the pitch-back type, c 9m in diameter and 0.75m in width with a gear, unusually outside the mill, driving a shaft passing through the mill. A rectangular iron box, a Penstock, recorded as on site but not seen, controlled the flow of water to the wheel through an iron pipe, still visible, from the pond behind. Wheel probably post 1860. Repaired 1923. Photo of 1936 shows wooden floats of the wheel and outer rim was in situ 1956. Part of millstone visible in garden of Mill Farm.


Corn-mill now disused. L-shaped plan, the straight joints and black mortar showing the extensions to the original E/W range. Of rubble, partly limewashed, with stone tile roof. Central L-shaped 2 storey unit has adjacent ground floor doorways, one cambered headed, one round-arched with gable apex openings. To left and right are lower wings with wide basket-arched openings for storage and carts, two on each side, and a further round-arched doorway end right. Ridge of the left wing blocks an opening of the central range and 3 full-height buttresses support the rear wall; gable end has a triangular ventilator. Right wing has 3 ventilation slits in gable end. Main range has to rear the remains of the metal hub to the mill wheel and the gears attached to the structure with metal support and opening beside.


Left wing has new roof structure; half height walls separate the bays; 2 further openings to main range gable end visible. Cobbled floors.

Reasons for Listing

Listed as a historic corn mill retaining much of its distinctive character; group value with the Forge.

Other nearby listed buildings

  • II Mill Forge
    On the southern border of Ystrad Mynach, on the W bank of Rhymney River, fronting the thoroughfare.
  • II Old Fire Station
    Originally situated off Park Road but now resited in grounds of Caerphilly County Borough Council offices at Ystrad Fawr, to W of main house.
  • II War Memorial
    Just off Caerphilly Road in a square to the north of Ysbyty Ystrad Fawr, approx. 50m W of the Old Fire Station (rec no 13569).
  • II Llanbradach Fawr
    Situated on the mountainside on the W slope of the Rhymney Valley, SW of Ystrad Mynach, and reached by a long lane from Llanbradach to S.
  • II Ystrad Mynach South Signal Box
    To the south of Ystrad Mynach station on the west side of the tracks off a rough lane from Twyn Road. Private property.
  • II Barn and stable range at Llanbradach Fawr
    Farmyard is on uphill side of the house and this barn is roughly parallel with the house.
  • II Church of Holy Trinity
    A472 skirts the W side of Ystrad centre; church is set back from the road on a knoll within a very hilly walled churchyard which falls away steeply to W and S, main entry at SE through lychgate.
  • II Taranymwrthwl Farm
    At the N end of the village and set back from the W side of the main road through Llanbradach.

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