©Crown Copyright. All rights reserved. Hertfordshire County Council, LA 076678, 2001
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©Crown
Copyright. All rights reserved. Hertfordshire County Council, LA 076678, 2001
Variable band on south-facing slope of Mimram valley between Digswell Water and the western edge of the Panshanger estate, west of Hertford. It is bounded to the south by the A414 and B1000 and includes part of the course of the river Mimram.
©Crown
Copyright. All rights reserved. Hertfordshire County Council, LA 076678, 2001
A consistent parkland character overlies any change in topography throughout this sinuous ribbon of floodplain pasture and woodland. Twentieth-century development and the busy transport network mask this character in some places.
Tewin Meadows bridge (HCC Landscape Unit)
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Geology and soils. Deep, well-drained fine loamy and sandy soils, locally flinty, over glaciofluvial drift (Ludford series).
Topography. River floodplain and gentle south-facing valley slopes.
Degree of slope. 1 in 40 (max).
Altitude range. 44m to 76m.
Hydrology. The Mimram is a relatively fast-flowing, gravel bedded chalk stream with a wide range of species and extensive marginal growth. It is one of the most natural rivers in the county, being least affected by abstraction and discharges, and is regarded by English Nature as the best chalk stream in East Anglia/Midlands. Fed by chalk springs, it flows mainly through parkland and agricultural land. Its middle reaches flow through several important wetland habitat complexes and the river is designated 'salmonid', indicating its suitability for trout and grayling.
Land cover and land use. This area consists of parkland, with a mix of pasture and wetland vegetation in the floodplain and arable and broadleaf woodland on the valley slopes. The primary land use is arable wooded farmland, while the secondary land uses include commercial ventures and pasture (cattle in parkland). There is evidence of significant farm diversification in ventures within this area, such as a change from farming to a hotel/conference centre and from watercress to fish farming.
Vegetation and wildlife. The woodland cover is very extensive, especially around the perimeter of the individual parklands, and the hornbeam at Marden Hill includes parkland pollards. Within the floodplain the dominant species is willow with alder; elsewhere the main mature species are hornbeam, oak and sweet chestnut. There are several notable veteran sweet chestnut at Tewin Water. In addition there are many mixed and variable young plantings, including conifers, generally associated with mineral extraction screening but in some instances likely to be relic game coverts. A series of alluvial meadows and marshes bordering the Mimram at Tewinbury is designated SSSI. It consists of mixed glyceria and reed swamp with associated carr developed in old cressbed lagoons; alder carr with rich ground flora; and neutral grassland (at Archers Green) with associated conservation species of green-winged orchid, snakeshead fritillary and corncrake. This is one of the most important species-rich river valley complexes in Hertfordshire. Rare invertebrates, otters and many bird species can be found in this area.
The historic pattern of this area is still apparent and widespread. It should be noted that the history of this area has been one of destruction and renewal since at least the mid-18th century, when the Earls Cowper bought up the notable houses around Tewin and demolished them, before building Panshanger. The modern road pattern tends to follow the historic park boundaries to north and south and there are no accessible internal roads or tracks within the parklands.
Field pattern. Field boundaries are either estate fencing or overgrown hedgerows, usually of oak or ash. Boundaries are more often oak or ash copses or plantation, to screen views in, frequently mature or over-mature. Field sizes vary from small (pasture) to medium (arable).
Transport pattern. The boundaries of the parklands are defined by the road network, with the B1000 marking the southern boundary of the area against the outskirts of Welwyn Garden City. Digswell Viaduct, at the western end of this area, marks the advent of the railway in the 19th century and is 'sometimes called one of the seven wonders of Hertfordshire' (Hertfordshire Countryside, Vol. 19, No.77, p.229).
Settlements and built form. There are no settlements within this area, which is characterised by country houses and isolated farms. Eighteenth-century red brick former stables can be found at Marden Hill Farm, together with a 16th-century weatherboarded barn and octagonal brick stockhouse. At Tewin Water Farm there is a brick lodge of oval plan, with a rustic portico of four tree-trunk columns.
Pevsner, N., rev. Cherrry, B., Hertfordshire, Penguin (2000).
English Heritage Register of Parks and Gardens.
Biodiversity Action Plan for Hertfordshire, pp. 54/55.
English Nature SSSI notification
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From outside, this area is largely concealed by boundary woodlands, with very limited views from the A414. Views within the area are very limited, due to lack of access, and are generally framed by wetland vegetation. The scale of the landscape elements is small to medium and it has a very contained, coherent character. It is not tranquil, with constant distant noise from road traffic.
Rarity and distinctiveness. Unusual area for its scale and the unity and completeness of the focus of the parkland on the river. This stretch of the Mimram has been highly regarded for its scenic beauty since at least the end of the 18th century (see below). The SSSI contains some county rarities.
Although new roads have in general followed old park boundaries, there is still a strong local impact from road transport and built development, such as farm diversification within the floodplain. The impact of land-use change within the area is less palpable. There has been some change from pasture or parkland to arable.
Noted recreational land uses: fishing (signs for).
Waymarked routes and footpaths are localised rather than widespread and there is no access to the private parklands
This is a distinctive and valued valley landscape(C).
'The whole of the beautiful valley from Welwin (sic) to Hertford, including Digswell, Tewin Water, Panshanger and Cole Green, belonging to the same noble family...while each possesses its independent privacy and seclusion, their united woods and lawns will by extending through the whole valley, enrich the general face of the county.' Repton in his Red Book of suggested improvements to Tewin Water for Henry Cowper, 1799
Landscape Conservation Area.
The lower Mimram is recognised as a High Biodiversity Area (HBA) for its wetlands and woodlands.
SSSI: Tewinbury.
Tewin Water is Grade II listed in the English Heritage
Register of Historic Parks and Gardens.
| CONDITION | |
|---|---|
| Land cover change: | insignificant |
| Age structure of tree cover: | mixed |
| Extent of semi-natural habitat survival: | extensive |
| Management of semi-natural habitat: | not obvious |
| Survival of cultural pattern: | widespread |
| Impact of built development: | localised |
| Impact of land-use change: | moderate |
| ROBUSTNESS | |
| Impact of landform: | apparent |
| Impact of land cover: | prominent |
| Impact of historic pattern: | continuous |
| Visibility from outside: | concealed |
| Sense of enclosure: | contained |
| Visual unity: | coherent |
| Distinctiveness/rarity: | unusual |
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Tewin Meadow (HCC Landscape Unit)
Footbridge over Tewin Water (P. Cullens)
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