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

Soussons Down (SX 676 803) – Sub-Four exclusion

There has been an exclusion from 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 Soussons Down (SX 676 803)

The criteria for the list that this exclusion 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 Soussons Down, 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 B4312 road to its north-west and minor roads to its south and east, and has the small community of Postbridge towards the west south-west.

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 an estimated c 16m of drop, based on the 420m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 404m col height, based on interpolation of 10m contouring between 400m – 410m. 

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 exclusion of this hill from Sub-Four status is due to LIDAR analysis, resulting in a 421.3m summit height and a 406.6m col height, with these values giving this hill 14.7m of drop, which is insufficient for it to be classified as a Sub-Four. 

 

The full details for the hill are:

Group:  High Willhays

Name:  Soussons Down

OS 1:50,000 map:  191

Summit Height:  421.3m (LIDAR)

Summit Grid Reference:  SX 67662 80357 (LIDAR)

Col Height:  406.6m (LIDAR)

Col Grid Reference:  SX 67766 80718 (LIDAR)

Drop:  14.7m (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

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (September 2026)