Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

The Welsh P15s – Hill Reclassifications

The Welsh P15s are all Welsh hills that have a minimum of 15m of drop, irrespective of their height.  Accompanying the main P15 list is a sub list entitled; The Welsh Sub-P15s, with the qualification to this sub category being all Welsh hills with 14m or more and below 15m of drop.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the additions, reclassifications and deletions to the main P15 list and the sub list that are below P20 and therefore documented in other lists, appear below presented chronologically in receding order.

Mapping Mountains - Hill Reclassifications - The Welsh P15s

Newry (SO 048 504) – Welsh P15 reclassified to Welsh Sub-P15 (73rd reclassification)

Significant Name Changes post for Newry

 

There has been a reclassification to the list of 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 Newry (SO 048 504)

The criteria for the list that this reclassification 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 Newry, and this was derived from the Tithe map, and it is adjoined to the Mynydd Epynt group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with the A470 road to its north and east, a minor road to its west and the B4520 road farther to its west, and has the town of Llanfair-ym-Muallt (Builth Wells) towards the north-west.

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 15m of drop, based on the 193m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 178m bwlch height, based on interpolation of 10m contouring between 170m – 180m. 

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.

Therefore, the reclassification of this hill to Welsh Sub-P15 status is due to LIDAR analysis, resulting in a 193.7m summit height and a 179.4m bwlch height, with these values giving this hill 14.2m 0f drop, which is insufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Mynydd Epynt 

Name:  Newry 

OS 1:50,000 map:  147

Summit Height:  193.7m (LIDAR)                                                           

Summit Grid Reference:  SO 04821 50490 & SO 04822 50491 & SO 04821 50493 (LIDAR)

Bwlch Height:  179.4m (LIDAR) 

Bwlch Grid Reference:  SO 04920 50451 (LIDAR) 

Drop:  14.2m (LIDAR) 

 

Myrddyn Phillips (December 2025)

Mapping Mountains - Hill Reclassifications - The Welsh P15s

Cae Cefn Issa (SN 692 009) – Welsh P15 addition (72nd reclassification)

Significant Name Changes post for Cae Cefn Issa

 

There has been an addition to the list of 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 Cefn Issa (SH 692 009)

The criteria for the list that this addition 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 listed by is Cae Cefn Issa, and this was derived from the Tithe map, and it is adjoined to the Tarren y Gesail group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its south, and has the town of Machynlleth towards the east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included in either the main list or the accompanying sub list, and was subsequently documented with an estimated c 13m of drop, based on an estimated c 120m summit height and an estimated c 107m bwlch height, with both heights based on interpolation of 10m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

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.

Therefore, the addition of this hill to Welsh P15 status is due to LIDAR analysis, resulting in a 119.5m summit height and a 103.9m bwlch height, with these values giving this hill 15.5m 0f drop, which is sufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Tarren y Gesail 

Name:  Cae Cefn Issa 

OS 1:50,000 map:  135

Summit Height:  119.5m (LIDAR)                                                           

Summit Grid Reference:  SH 69202 00955 (LIDAR)                                                  

Bwlch Height:  103.9m (LIDAR) 

Bwlch Grid Reference:  SH 69081 01055 (LIDAR) 

Drop:  15.5m (LIDAR) 

 

Myrddyn Phillips (December 2025)

Mapping Mountains - Hill Reclassifications - The Welsh P15s

Cae Grib (SN 679 992) – Welsh P15 addition (71st reclassification)

Significant Height Revisions post for Cae Grib

Significant Name Changes post for Cae Grib

 

There has been an addition to the list of 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 Grib (SN 679 992)

The criteria for the list that this addition 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 listed by is Cae Grib, and this was derived from the Tithe map, and it is adjoined to the Tarren y Gesail group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its immediate north-west, and has the small community of Cwrt towards the north-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included in the main P15 or Sub P14 list, as with no significant contours of note on the Ordnance Survey 1:25,000 Explorer map, it was difficult to ascertain if any hill with relevant prominence existed. 

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.

Therefore, the addition of this hill to Welsh P15 status is due to LIDAR analysis, resulting in a 45.4m summit height and a 29.95m bwlch height, with these values giving this hill 15.4m 0f drop, which is sufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Tarren y Gesail 

Name:  Cae Grib 

OS 1:50,000 map:  135

Summit Height:  45.4m (LIDAR)                                                           

Summit Grid Reference:  SN 67980 99200 (LIDAR)                                                  

Bwlch Height:  29.95m (LIDAR) 

Bwlch Grid Reference:  SN 67971 99264 (LIDAR) 

Drop:  15.4m (LIDAR) 

 

Myrddyn Phillips (November 2025)