Mapping Mountains – Summit Relocations – The Fours – The 400m Hills of England

 

Buttern Hill (SX 652 885) 

There has been a Summit Relocation to a hill that is listed in the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Buttern Hill (SX 652 885)

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

The Fours – The 400m Hills of England - English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list is a sub list entitled the Sub-Fours, the criteria for which are all English hills at or above 400m and below 500m in height that have 15m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available to download in Google Doc format from the Mapping Mountains site.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Buttern Hill, and it is adjoined to the High Willhays group of hills, which are situated in the south-west of England, and it is positioned with a series of minor roads towards its east, and has the town of Chagford towards the east.

When the Introduction to the first group of hills for the updated and revised listing of the The Fours – The 400m Hills of England was published by Mapping Mountains on the 10^th September 2022, it was announced that the accompanying sub lists were being revised with the two 390m categories dispensed with and the criteria and name of the 400m Sub-Fours revised.  The one accompanying sub list is now named the Sub-Fours with its criteria being all English hills 400m and above and below 500m in height that have 15m and more and below 30m of drop.

Prior to this revision this hill was listed with 18m of drop, based on the 413m summit spot height positioned at SX 65283 88668 that appears on the Ordnance Survey 1:25,000 Explorer map and the 395m col spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.  With the caveat that the Ordnance Survey 1:50,000 Landranger map has a 413m spot height positioned at SX 65308 88423. 

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 summit image of Buttern Hill (SX 652 885)

LIDAR analysis gives the highest ground on this hill as 414.3m positioned at SX 65272 88551, and when compared to its originally listed summit position 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 summit height produced by LIDAR analysis is 414.3m and this is positioned at SX 65272 88551.  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 117 metres southward from where the originally listed summit is positioned.

 

The full details for the hill are:

Group:  High Willhays

Name:  Buttern Hill

OS 1:50,000 map:  191

Summit Height:  414.3m (LIDAR)

Summit Grid Reference (New Position):  SX 65272 88551 (LIDAR)

Col Height:  395.9m (LIDAR)

Col Grid Reference:  SX 64912 88541 (LIDAR)

Drop:  18.3m (LIDAR)

 

Myrddyn Phillips and Aled Williams (September 2026)

Mapping Mountains – Hill Reclassifications – 500m Twmpau

 

Llechwedd Deiliog (SH 785 398) – 500m Sub-Twmpau addition

There has been confirmation of an addition to the listing of the 500m Twmpau that is retrospective, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams and subsequent LIDAR analysis conducted by Aled Williams. 

LIDAR image of Llechwedd Deiliog (SH 785 398)

The criteria for the list that this addition applies to are:

500m Twmpau - Welsh hills at or above 500m and below 600m in height with 30m minimum drop, with an accompanying sub list entitled the 500m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 500m and below 600m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is available to download in Google Doc format from Mapping Mountains.

500m Twmpau by Myrddyn Phillips

The name the hill is listed by is Llechwedd Deiliog and it is adjoined to the Arenig Fach group of hills, which are situated in the central part of North Wales (Region C1, Sub-Region C1A), and it is positioned with the B4391 road to its south, and has the village of Trawsfynydd towards the west south-west. 

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

When the list that later became known as the 500m Twmpau was first compiled, this hill was not included in the accompanying sub list, but was later added after a basic levelling survey conducted by Myrddyn Phillips on the 16.05.04 gave it 66½ft (20.3m drop).

This hill is also included in the listing of The Welsh Highlands – Uchafion Cymru co-authored by Myrddyn Phillips and Aled Williams and it formed one of a number of hills held back from publication until this list was published in its entirety.  However, this policy has now changed; therefore the details for this hill have been put in the public domain. 

The Trimble set-up position at SH 78452 39920 with subsequent LIDAR analysis prioritised

However, it was not until a Trimble GeoXH 6000 survey and 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. 

The Trimble GeoXH 6000 gahering data at the bwlch of Llechwedd Deiliog

Therefore, the confirmation of the addition of this hill to 500m Sub-Twmpau status is due to a Trimble GeoXH 6000 survey and LIDAR analysis, resulting in a 501.7m summit height and a 481.2m bwlch height, with these values giving this hill 20.6m of drop, which is insufficient for it to be classified as a 500m Sub-Twmpau.

 

The full details for the hill are:

Group:  Arenig Fach

Name:  Llechwedd Deiliog

OS 1:50,000 map:  124

Summit Height:  501.7m (LIDAR) 

Summit Grid Reference:  SH 78522 39815 (LIDAR) 

Bwlch Height:  481.2m (converted to OSGM15, Trimble GeoXH 6000) 

Bwlch Grid Reference:  SH 78298 40196 (Trimble GeoXH 6000) 

Drop:  20.6m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Myrddyn Phillips (September 2026)

Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Braich Bryn Engan (SH 723 569) – Welsh P15 addition 

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 Braich Bryn Engan (SH 723 569)

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 Braich Bryn Engan, and it is adjoined to the Moel Siabod group of hills, which are situated in the north-western part of North Wales (Region C1, Sub-Region C1A), and it is positioned with the A4086 road to its north-west and the A5 road to its north-east, and has the village of Capel Curig towards the north.

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, with subsequent interpolation giving the hill as estimated c 336m summit height and an estimated c 323m bwlch height, with both heights based on interpolation of 10m 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.

Therefore, the addition of this hill to Welsh P15 status is due to LIDAR analysis, resulting in a 338.1m summit height and a 319.8m bwlch height, with these values giving this hill 18.4m 0f drop, which is sufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Moel Siabod 

Name:  Braich Bryn Engan 

OS 1:50,000 map:  115

Summit Height:  338.1m (LIDAR)                                                           

Summit Grid Reference:  SH 72354 56932 (LIDAR)                                                  

Bwlch Height:  319.8m (LIDAR) 

Bwlch Grid Reference:  SH 72162 56912 (LIDAR) 

Drop:  18.4m (LIDAR) 

 

Myrddyn Phillips (September 2026)

 

Mapping Mountains – Summit Relocations – Y Pellennig – The Remotest Hills of Wales, The Welsh Highlands – Uchafion Cymru and 600m Twmpau

Carnedd Llechwedd Llyfn (SH 857 444) 

There has been a Summit Relocation to a hill that is listed in the Y Pellennig – The Remotest Hills of Wales, The Welsh Highlands – Uchafion Cymru and the 600m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

LIDAR image of Carnedd Llechwedd Llyfn (SH 857 444)

The criteria for the three listings 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 Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

The Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips

600m Twmpau - Welsh hills at or above 600m and below 700m in height with 30m minimum drop, with an accompanying sub list entitled the 600m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 600m and below 700m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is available to download in Google Doc format from Mapping Mountains. 

600m Twmpau by Myrddyn Phillips

The name the hill is listed by is Carnedd Llechwedd Llyfn and it is adjoined to the Carnedd y Filiast group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A1), and it is positioned with minor roads to its north-west and north-east, the A5 road farther to its north, the B4407 road farther to its north-west and the A4212 road to its south, and has the town of Y Bala towards the south-east.

When the original list that later became known as the The Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with an estimated c 25m of drop, based on the 643m summit spot height positioned at SH 85778 44459 that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and an estimated c 618m bwlch height, based on interpolation of 10m contouring between 600m – 610m. 

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

Since the original compilation of these lists there have been a number of maps made available online.  Some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website.  Whilst others were digitally updated such as the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a twin 643m summit spot height positioned at SH 85789 44665 (latterly shown on the DataMapWales) and a 618m bwlch spot height, with these values giving this hill 25m of drop and resulting in the hill being listed as a twin top. 

Extract from the DataMapWales

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 summit image of Carnedd Llechwedd Llyfn (SH 857 444)

The height produced by LIDAR analysis to the summit of this hill is 644.1m and is positioned at SH 85783 44460, whilst LIDAR gives the highest ground adjacent to where the 643m spot height appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map as 643.6m positioned at SH 85785 44677 and SH 85782 44676 and SH 85785 44674 and SH 85779 44667, 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 644.1m and this is positioned at SH 85783 44460 and this was derived from LIDAR analysis, this position approximately matches that of the spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and has resulted in the de-twinning of this hill.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Carnedd y Filiast

Name:  Carnedd Llechwedd Llyfn

OS 1:50,000 map:  124, 125

Summit Height:  644.1m (LIDAR) 

Summit Grid Reference (New Position):  SH 85783 44460 (LIDAR) 

Bwlch Height:  618.7m (LIDAR) 

Bwlch Grid Reference:  SH 86005 44925 (LIDAR) 

Drop:  25.4m (LIDAR) 

Remoteness:  2.860km

 

Myrddyn Phillips and Aled Williams (September 2026) 

Mapping Mountains – Hill Reclassifications – The Fours – The 400m Hills of England

Hound Tor (SX 628 890) – 400m Sub-Four addition

There has been an addition that is retrospective to the listing of the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Hound Tor (SX 628 890)

The criteria for the list that this addition applies to are (prior to incorporating P15s as subs): 

The Fours – The 400m Hills of England.  English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list are three categories of sub hills, with this hill being added to the 400m Sub-Four category, the criteria for which are all English hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and the 2^nd edition of the booklet containing this list was published by Mapping Mountains Publications on the 24^th April 2018.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Hound Tor and it is adjoined to the High Willhays group of hills, which are situated in the south-west of England, and it is positioned with the A30 to its north, and has the town of Okehampton towards the north-west.

When the 2^nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, this hill was not included as it was listed with 19m of drop, based on the 495m summit spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map and the 476m col spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage 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 400m Sub-Four status is due to LIDAR analysis, resulting in a 495.5m summit height and a 473.7m col height, with these values giving this hill 21.8m of drop, which is sufficient for 400m Sub-Four status.

 

The full details for the hill are:

Group:  High Willhays

Name:  Hound Tor

OS 1:50,000 map:  191

Summit Height:  495.5m (LIDAR)

Summit Grid Reference:  SX 62878 89012 (LIDAR)

Col Height:  473.7m (LIDAR)

Col Grid Reference:  SX 63275 89559 (LIDAR)

Drop:  21.8m (LIDAR)

 

For the additions, deletions and reclassifications to The Fours – The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1^st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

The Fours – 400m Sub-Four

 

The Fours – 390m Sub-Four

 

The Fours – 390m Double Sub-Four

 

Myrddyn Phillips and Aled Williams (September 2026)