Mapping Mountains – Summit Relocations – The Welsh P15s

Cae Llidiart Fawr (SJ 085 095) 

There has been a Summit Relocation to a hill that is listed in the The Welsh P15s, 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 Cae Llidiart Fawr (SJ 085 095)

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

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The name the hill is now listed by is Cae Llidiart Fawr, and this was derived from the Tithe map, and it is adjoined to the Esgeiriau Gwynion group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned with minor roads to its north, west and east, with the A458 road and the A495 road to its south, and has the town of Llanfair Caereinion towards the south south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the main list with an estimated c 17m of drop, based on an estimated c 191m summit height positioned at SJ 08517 09520 and an estimated c 174m bwlch height, with both heights based on interpolation of 5m contouring. 

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 190.7m positioned at SJ 08508 09511.  However, this is to the top of a hedge bank 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 of Cae Llidiart Fawr (SJ 085 095)

The height produced by LIDAR analysis to the highest remaining natural ground of this hill is 190.1m and is positioned at SJ 08505 09512, 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 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 summit height produced by LIDAR analysis is 190.1m and is positioned at SJ 08505 09512, this position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and is approximately 3 metres west north-westward from where the high point of the hedge bank is positioned. 

 

The full details for the hill are: 

Group:  Esgeiriau Gwynion 

Name:  Cae Llidiart Fawr 

OS 1:50,000 map:  125

Summit Height:  190.1m (LIDAR)                                                           

Summit Grid Reference (New Position):  SJ 08505 09512 (LIDAR)                                                  

Bwlch Height:  173.8m (LIDAR) 

Bwlch Grid Reference:  SJ 08871 09602 (LIDAR) 

Drop:  16.3m (LIDAR) 

 

Myrddyn Phillips (May 2025)