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HER Number:MDV18410
Name:Foul water prison Leat, Princetown


Leat running from the prison to land at Tor Royal.


Grid Reference:SX 606 729
Map Sheet:SX67SW
Admin AreaDartmoor National Park
Civil ParishDartmoor Forest
DistrictWest Devon
Ecclesiastical ParishLYDFORD

Protected Status

  • SHINE: Extensive earthwork and structural remains of the late 18th century Devonport Leat, Bronze Age features north-east of Nun’s Cross, Whiteworks Tin Mine and other tinning remains on Walkhampton Common as well as earthworks of Bachelors Hall Mine

Other References/Statuses

  • Old DCC SMR Ref: SX67SW/133
  • SHINE Candidate (Yes)

Monument Type(s) and Dates

  • LEAT (XVIII to XIX - 1800 AD to 1809 AD (Between))

Full description

DNP, Untitled Source (Migrated Record). SDV265766.

Leat shown on dnp tor royal survey - runs sx61077243 to sx61457215 (dnp).

RCHM APP 1985, Untitled Source (Migrated Record). SDV265767.

Not visible (rchm app 1985).

RCHME, Untitled Source (Report - Survey). SDV265768.

Vis=21/4/1989 (rchme) foul leat. Constructed early 19c to convey sewage effluent from the princetown war prison to tor royal newtake probably to fertilise the pasture on royal hill. It is on the contour very close to and just higher than the devonport leat which in fact it crossed at one place giving rise surely to problems of occasional pollution.

HOUSE, Untitled Source (Report - Survey). SDV265769.

Vis=an early 19c duchy map depicts its course from the blackbrook river, presumably the source of fresh flowing water into the ne side of the prison enclosure out of the s side across a stream to the n boundary of tor royal (house); midway it is annotated "foul leat (1812) or bachelors hall mine leat (1806)". From tor royal its sinuous route crosses the devonport leat and runs around the s side of royal hill apparently cutting through a series of ditched field plots on the way. Here it is annotated "foul leat" and was presumably unfinished.

Untitled Source (Report - Survey). SDV265770.

Vis=the 1839 tm depicts more or less the same route but also shows its complete course from the bifurcation on the w side of royal hill, its line around both flanks of the hill to the meeting point near the head of the lanson brook.

Untitled Source (Migrated Record). SDV265772.

Des=dnp survey (6") of tor royal farm/(1982)in smr.

Untitled Source (Migrated Record). SDV265773.

Hemery, e. /high dartmoor/(1983)390.

Untitled Source (Migrated Record). SDV265774.

?/follow the leat/(1983)54.

Untitled Source (Migrated Record). SDV265775.

Des=duchy of cornwall/map of freeholds and early enclosures on dartmoor/(1805-18).

Untitled Source (Migrated Record). SDV265776.


Untitled Source (Migrated Record). SDV265777.

Des=probert, s. A. J. /(21/4/1989)/rchme field investigation.

Joy, R., 2002, Dartmoor Prison A Complete Illustrated History Volume 1 The War Prison 1809-1816 Parcere Subjectis, 28-30, figures (Monograph). SDV359842.

Water supply to the war prison was established by 1809 and was in use until the 1990s, when it was disconnected. A water course was surveyed and built, running from Spriddle Lake, a tributary of the River Walkham (SX585803) about four miles from the prison, finishing up at the reservoir outside the gates of the prison (MDV27089). From the reservoir (MDV42843), water was fed into a round water tower, inside which were five bibcocks (A-E) which controlled the water, as required, into five open leats that then flowed into different parts of the prison. These fed out into the foul water leat, which collected foul water from the slaughterhouse and then proceeded to Tor Royal and was distributed over the land below a hill called Broken Barrow. The final part of the foul leat on prison land, nearest its exist from the war prisons, was filled in by contractors laying new drains in the 1980s.

Stanbrook, E., 2002, Dartmoor's War Prison & Church 1805-1817, 85-6 (Monograph). SDV359848.

There were problems with setting up of the foul water leat from the prison. In 1808 Thomas Tyrwhitt, who was interested in using the 'foul water' from the prison to fertilising his lands at Tor Royal, applied to the prison Board to get it diverted. Originally the plan had been to divert it to the Blackabrook, channelling over or under the Devonport Leat. After some argument and negotiation, Tyrwhitt was able to get his way. Parts of the dry course of the leat can still be traced.
Both least were troubled during the first few years; bad weather caused them to freeze solid in 1809 and a year later they were in such a bad condition that they required deeper digging and lining with bigger stones. By October 1810, it was decided to lower the clean water course and have it covered.

National Monuments Record, 2010, Untitled Source (National Monuments Record Database). SDV214864.

Vis=foul leat can be traced for much of its course from dartmoor prison to the e flank of royal hill. Short stretches have been either effaced or ploughed down but elsewhere, now dry and silted, it is on average 0.7m wide and 0.3m deep, with a slight earthen bank on the downhill side. From the prison to the crossing point of a small stream (sx58977369) in prison property it was not investigated. From here to the road (sx59337396) it has been effaced by agricultural activity. It then follows the 405m contour along the upper side of a field bank, through the bachelors hall tin mine complex (sx59817346)(where at some time it has been breached) across the cultivated inbye fields to the rear of tor royal (sx59907313). It runs along and down a steep e slope through woodland to the lip of a quarry (sx67sw/292) where its course is confused by shallow drainage ditches. At the foot of the quarry scoop at 396m a well-constructed causeway 4.9m wide and a maximum 1.3m high, faced with coursed moorland stoned, indicates the line to where it crossed the devonport leat (sx60167244), probably by a wooden launder. Beyond, its course across low-lying marshy ground to sx60447280 is represented by a c.2m wide slightly raised peat strip with some stones and boulders, bounded by peat-cutting headlands. The effluent was conveyed across this marsh presumably also by a wooden launder. It bifurcates at sx60447281 and skirts both flanks of royal hill, occasionally winding its way through dense patches of earthfast boulders, to terminate at 387m in the silted headwaters of lanson brook, at sx61867225 (probert).

Sources / Further Reading

SDV214864National Monuments Record Database: National Monuments Record. 2010. National Monuments Record Database. Website.
SDV265766Migrated Record: DNP.
SDV265767Migrated Record: RCHM APP 1985.
SDV265768Report - Survey: RCHME.
SDV265769Report - Survey: HOUSE.
SDV265770Report - Survey:
SDV265772Migrated Record:
SDV265773Migrated Record:
SDV265774Migrated Record:
SDV265775Migrated Record:
SDV265776Migrated Record:
SDV265777Migrated Record:
SDV359842Monograph: Joy, R.. 2002. Dartmoor Prison A Complete Illustrated History Volume 1 The War Prison 1809-1816 Parcere Subjectis. Dartmoor Prison A Complete Illustrated History. 1. Hardback Volume. 28-30, figures.
SDV359848Monograph: Stanbrook, E.. 2002. Dartmoor's War Prison & Church 1805-1817. Dartmoor's War Prison & Church 1805-1817. Paperback Volume. 85-6.

Associated Monuments

MDV15309Related to: Dartmoor Prison, Princetown (Building)
MDV26101Related to: Granite quarries east of South Plantation (Monument)
MDV27089Related to: Prison Leat, Dartmoor Forest (Monument)
MDV117272Related to: Prison slaughterhouse, princetown (Building)
MDV51417Related to: Quarry north of Princetown (Monument)
MDV121049Related to: Quarry north-west of New London Cottages, Princetown (Monument)

Associated Finds: none recorded

Associated Events: none recorded

Date Last Edited:Jun 12 2018 4:18PM