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

Royal Hill (SX 606 733) 

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 initially conducted by Aled Williams and subsequently by Myrddyn Phillips. 

LIDAR image of Royal Hill (SX 606 733)

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 are three categories of sub hills, with this hill being included in 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 Royal Hill, and it is adjoined to the High Willhays group of hills, which are situated in Dartmoor in the south-west of the country, and it is positioned with the B3357 road to its north-east, the B3212 road to its north-west and a minor road to its south-west, and has the village of Princetown towards the west north-west. 

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

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, this hill was listed with 21m of drop, based on the 413m summit spot height positioned at SX 61197 72800 and the 392m col spot height, both of which appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, and this is also the position the summit was listed as when the 2^nd edition of The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018.

However, it was not until the latest LIDAR became available that the details for this hill could again 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 Royal Hill (SX 606 733)

Using the latest 1m DSM LIDAR model gives the top positioned at SX 61170 71814 as 412.060m in height and the summit positioned at SX 60699 73336 as 412.111m in height, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to when the high point is positioned in a different field, to a different feature such as a conifer plantation, within a different map contour, a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit 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 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 412.1m and this is positioned at SX 60699 73336.  This position is given a 412m spot height on the contemporary Ordnance Survey 1:25,000 Explorer map and is approximately 520 metres north-westward from where the previously listed summit is positioned.

 

The full details for the hill are:

Group:  High Willhays

Name:  Royal Hill

OS 1:50,000 map:  191

Summit Height:  412.1m (LIDAR)

Summit Grid Reference (New Position):  SX 60699 73336 (LIDAR)

Col Height:  391.2m (LIDAR)

Col Grid Reference:  SX 60181 72633 (LIDAR)

Drop:  20.9m (LIDAR)

 

Myrddyn Phillips and Aled Williams (February 2024)