Mapping Mountains – Summit Relocations – Y Pellennig – The Remotest Hills of Wales

Graig Wen (SN 786 629) 

There has been a Summit Relocation to a hill that is listed in the Y Pellennig – The Remotest Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Graig Wen (SN 786 629)

The criteria for the list that this summit relocation applies to are:

Y Pellennig –The Remotest Hills of Wales - Welsh hills whose summit is at least 2.5km from the nearest paved public road and the hill has a minimum 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on Mapping Mountains to download in Google Doc format. 

Y Pellennig - The Remotest Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Graig Wen, and this was derived from local enquiry and it is adjoined to the Esgair Wen group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north-west and the B4343 road farther to its north-west, and has the village of Pontrhydfendigaid also towards the north-west.

When the listing that became known as the Y Pellennig – The Remotest Hills of Wales was first compiled, this hill was listed with an estimated c 16m of drop, based on the 479m summit spot height positioned at SN 78618 62909 that appears on the Ordnance Survey 1:25,000 Explorer map, and an estimated c 463m bwlch height, based on interpolation of 10m contouring between 460m – 470m. 

Extract from the Ordnance Survey 1:25,000 Explorer map

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

LIDAR analysis gives the highest ground on this hill as 479.3m positioned at SN 78613 62923.  However, this is to the top of what LIDAR indicates is a raised ridge line of trees and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill. 

LIDAR summit image o Graig Wen (SN 786 629)

The summit area of this hill is intermittently covered by conifer plantation and therefore this whole area has been disturbed by man, however the height produced by LIDAR analysis to the highest centralised contour and to what could be deemed the natural summit of this hill is 479.2m and is positioned at SN 78619 62908, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour either on Ordnance Survey maps or interactive mapping, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or the listing of a new twin summit or de-twinning of a summit, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the new listed summit height of this hill is 479.2m and this is positioned at SN 78619 62908 and this was derived from LIDAR analysis, this position is approximately 15 metres south south-eastward from where the high point of the raised line of trees is positioned.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Esgair Wen

Name:  Graig Wen

OS 1:50,000 map:  146, 147

Summit Height:  479.2m (LIDAR) 

Summit Grid Reference (New Position):  SN 78619 62908 (LIDAR) 

Bwlch Height:  459.9m (LIDAR) 

Bwlch Grid Reference:  SN 78426 63149 (LIDAR) 

Drop:  19.3m (LIDAR) 

Remoteness:  3.000km

 

Myrddyn Phillips and Aled Williams (February 2026)