MSO7020 - 19th Century contour leat from Great Buscombe to Swap Hill (Monument)

A substantial contour leat is visible as an earthwork on aerial photographs, running from Great Buscombe to Swap Hill. It is thought to date to the mid 19th Century and the earlier phase of agricultural improvements by the Knight family.

A contour leat, 4 kilometres long, runs from Great Buscombe to Swap Hill. At SS 8120 4105, it is 3.6 metres wide and 0.7 metres deep, with the bank 2.5 metres wide and 1.1 metre high on the downslope side. Some large stones have been used in its construction. The leat predates the 19th Century field boundaries that cut through it. [1] A grass covered linear earthwork, centred SS 8140 4231, lies 800 metres to the southwest of Larkbarrow farmhouse on the north facing slopes of Swap Hill. The feature is situated at about 400 metres above Ordnance Datum and comprises a ditch and bank, running to almost 500 metres in length. It is most probably a contour leat, constructed to carry water from the Swap Hill spring to the field gutter system on the slopes of Long Combe (MSO7028), dating from the mid 19th Century. The leat was recorded at 1:2500 scale using differential GPS as part of an archaeological survey of the Larkbarrow area. The survey was undertaken by the Exeter office of English Heritage at the request of the Exmoor National Park Authority. A client report was produced as part of the survey work and is available from the NMRC, Swindon. [6,10] A substantial contour leat is visible as an earthwork on aerial photographs, running from Great Buscombe to Swap Hill. Beginning at approximately SS 7809 4205, the leat follows the line of the 410 metre contour line for approximately 3.6 kilometres, fading from sight at SS 8165 4238. In several places the leat is cut by 19th Century field boundaries, on Trout Hill for example, indicating that it predates these features. The leat also lies within an area of extensive 19th Century drainage ditches, some of which cut through the the leat. It seems likely that this feature dates to the mid 19th Century and the earlier phase of agricultural improvements by the Knight family. [4,7,8] This record was enhanced as part of the National Record of the Historic Environment to Exmoor National Park Historic Environment Record data transfer project. [11,12] As part of the Exmoor Mires Project, in 2013 Cornwall Council Historic Environment Service were contracted to undertake a non-intrusive walkover survey of the proposed mire restoration area on Lanacombe, which included this site. SS 78199 42058. A contour leat on Trout Hill formed by a ditch 2 to 3 metres wide with a bank 3 metres wide and up to 0.6 metres high on its downslope (northern) side. The bank is generally flat topped and has sloping sides; occasional stone is visible in its makeup but there is no visible revetting of the faces. The western end runs out at the break of slope above a combe on the east side of Great Buscombe. There is one break in the bank. The portion of the leat within the survey area divides two distinct alignments (? phases) of drainage ditches, suggesting that it was already extant when these were constructed. The bank is cut by, and therefore pre dates, the broadly northeast to southwest boundary crossing Trout Hill which is said to form part of the 19th Century Knight family improvement of the former Forest of Exmoor (MMO 2407). [13] The visit was followed by a further survey undertaken by The Historic Environment Officer for the Exmoor Mires Project. The site was photographed but no mention was made of it in the follow up report. [14] The site was subject to restoration work as part of work undertaken at The Warren as part of the Exmoor Mires Project during March 2016 and August 2016 to January 2017. None of the leat was affected by the restoration works; however, it was noted on site that significant damage was being caused to the feature by heavy access use and subsequent water channelling and erosion. At one point, a ditch that was being blocked crossed the leat. Here, 20 metres were left at either side of the leat to avoid any interference with it. However, it was badly eroded here and may require further attention to avoid further erosion and damage. At other points in Beckham, the leat had been damaged by pathways or water channels. [15] A metric survey of part of a contour leat on Swap Hill was carred out in July and August 2019. The leat is part of an extensive irrigation system constructed by John Knight in Exmoor Forest in 1819 and 1820 to improve grazing. [16]