Clausentum Fen has a fascinating, very long but often, somewhat obscure history! What is clear, however, is that it formed a distinct area from earliest times.

Originally the Itchen together with subsidiary brooks, flowed as a multi-braided channel across a wide and boggy floodplain, punctuated by slightly higher gravel islands and occasional swampy meres. It is likely that Clausentum Fen was part of a valley peatland complex that extended along the Itchen. The earliest settlements were on the hills overlooking the valley with iron age forts at Oram's Arbour and St Catherine's Hill. Pre-historic fords crossed the valley's many channels.

The Romans, fortified one of these (43AD), founding the first settlement in the valley, Venta Belgarum, and began drainage works and controlling the river's erratic courses. The Saxon King Alfred (871-899) established his largest fortified burgh on the site and appears to have brought the Lower and Middle Brooks within the walls to encourage people to live in the city. The Worthy Brook (Upper Brook/Kings Brook) was controlled to supply water both to Hyde Abbey, and the royal palace in the city. Bishop Aetholwold (962-984) introduced the Benedictines to Winchester and redirected the brooks again to form conduits and drains for the new monastic buildings, which included a 46 hole lavatorium for the monks. One branch, served later as the Winchester College drain and then, utilising the earlier St Michael's stream, flowed on to Prior's Barton. The main drain, the Lockburn, flowed on to the Hospital at St Cross (founded 1132), and forms the eastern boundary of the Fen. At some point it was raised as a mill leat, and used by the many mills between the city and St Cross; running above floodplain level until it emptied into the Itchen beyond the Hospital, it cut off the Fen from the rest of the floodplain.

The result of this was that bourne streams and ancient drains to the south of the city and to the west of the Lockburn could no longer reach the Itchen and drained instead into the Fen. The southern half had always been very low lying and formed a large mere. Although this silted up and was partly reclaimed through the medieval period - to the point that it was called Godspit Mere - in times of heavy rain all the flows from the Western slopes of the Itchen and from the south of the city concentrated on the Fen. It may be that the Lockburn aqueduct and culvert beneath (constructed in 1420, if not earlier), together with the high baulk in the southern fen, were built to relieve flooding and to direct water back to the floodplain and Itchen. The bank at the southern end of the Fen, dividing it from the School Environmental Centre is certainly ancient, marking the northern extent of the Soke lands of St Cross Hospital.

Clausentum Fen's northern limit was marked by the Heywardespath, a ford, which roughly followed the line of Garnier Road to cross the West Itchen via a gravel island. To the south a second ford followed the line of Christ-stead/Cripstead/Water Lane to reach gravel islands, east and west of the Itchen, where in medieval times the grazing marsh and hay meadows were situated. The two gravel islands in the north marked the western and eastern limits of the Fen. On the western island was 'Christ-stead', subsequently Prior's Barton, the early medieval monastic grange farm belonging to the Prior of St Swithun's (the Cathedral Benedictine Priory). This was an important moated site. It was incorporated later into the Soke lands of the Bishops of Winchester and there is reference to two mills, and a fishery. The Barton mills were situated on the gravel island to the East of the Fen. One was burnt down during the Civil Wars(1215-16) at the time of King John. There are records that the revenue from the Barton Mill declined from £5 to £3 3s following the Black Death (1349), but the mills were rebuilt and revenue recovered. By Henry VII's reign the fulling Mill at Prior's Barton with the fishery appurtenant was farmed at £9. These were very significant sums!

The monks of Prior's Barton were certainly engaged in the profitable wool trade; there was at least one fulling mill at Barton but whether the Fen was utilised for grazing in the Medieval period is much less clear. It may well have been too marshy and wet.

Following the Reformation, much monastic property was sold off but Clausentum Fen, protected as part of the Bishop of Winchester's Soke, remained in ecclesiastical hands. At some point Prior's Barton itself was sold and later became a Georgian country residence. The Reformation did, however, impact on the Fen. New landowners in Hampshire brought in Dutch engineers to drain and reclaim unprofitable floodplains and they introduced the system of water meadows. By both drowning and draining the meadows with a system of header courses, ditches and panes, early rich meadow grass was produced, allowing grazing and the production of spring lambs for the London market. Once grazed the sheep were removed and the meadows re-drowned to produce further grass and later hay crops. The new system was introduced into Winchester from 1635 and at the same time, more powerful but fewer mills replaced smaller medieval ones. The West Itchen was straightened destroying the Cripstead /St Faith's grazing meadow and the Cobb water meadows beyond replaced the old common grazing marsh. The Lockburn now served as a header channel for meadows as far south as Shawford.

However, Clausentum Fen itself does not appear to have had a water meadow introduced until at least 1740. It may just have been too low lying and wet. The first drawn water system utilised the pre-existing, eastern and western water courses. The western channel was at some point raised to gain sufficient height for the header to reach the southern part of the fen, and appears to have run all along the western edge of the Fen following roughly the former course of St Michael's Brook. It must have been costly to install the drains and panes needed to drown the meadow and no evidence of them now exists in the northern two compartments of the Fen. It is assumed that at this time the Fen was used for grazing.

Hugh Corry suggests that the water meadow on the Fen was very unconventional and elaborate for so small an acreage. He believes that 'the cost was no object to the Church, but laying out such a system for its own sake seems rather improbable, if not driven by other considerations' . He suggests that it functioned as a flood control measure not just for the locality but for the whole Fulflood catchment and also enabled land reclamation to the west.

Water meadow systems fell out of use in the late 19th century when the development of artificial fertilisers, new grass strains and fodder crops allowed improved pastures elsewhere and competition grew for the spring lamb market. Drowning was labour intensive and expensive and the returns no longer justified it. Almost all water meadow systems were abandoned or destroyed in the first half of the 20th century but the decline on the Fen probably started even earlier.

A map of 1897 shows considerable alteration to the drainage following the enlargement of Winchester College cricket ground. Only a small portion of the adjacent College meadows survived and the old western Prior's Barton carrier (St Michael's stream) across College meads was either put under ground or even filled in. A new carrier was constructed for the Fen off the Lockburn/West Barton Mill Leat and ran alongside, then under, Garnier road to join the old Prior's Barton channel. It probably was built at a higher level to pass over other channels closed or sunk at the same time. The flow may not have been as good as before and water meadow operation in the northern part of Clausentum Fen ceased by 1898. By 1909 the surviving remnant of Winchester College meadow disappears from the maps along with the eastern water course and culvert which had fed the Clausentum Fen eastern brook. It is a mystery whether this was put underground or whether any water still reaches the Fen from this source.

In the 20th century Prior's Barton acquired the northern half of the Fen as a garden, or 'wilderness' extension. Many native and non-native trees and shrubs were planted at this time but it was abandoned after the Second World Ward, and the growing woodland left to nature. Grazing on the southern Fen seems to have ceased by 1950.

The Church Commissioners gradually sold off their remaining land and new roads (St Faith's and Clausentum) and mainly terraced housing were built from 1910 on the gravel terraces to the west of the Fen. Development on the southern half of the Fen was also considered but it proved too wet and in 1934 the Church Commissioners sold the Fen. At some point it was acquired by Perbury Homes who trading as PGC Construction Ltd in 2003, sold a 999 year lease of the land as 'a nature conservation area general woodland and meadowland' to Hampshire County Council.

The Fen, after 1950, gradually reverted to nature; scrub and secondary woodland encroached, a sycamore tree broke the culvert which fed water to the southern half and the fen began to dry out. Mike Gibbon's submission of detailed species lists achieved SINC (Site of Importance for Nature Conservation) status for Clausentum Fen in 2003 and it was included in the South Downs National Park when it was established in 2010.

OS map 1873 (surveyed 1869-70)
Aerial photo of the Fen in 1949
Illuminations from the Bedford Book of Hours (c1410-30)

  • A peasant scything a meadow from the calendar page for June.
  • A ram from March.