Panshanger Park and the River Mimram that flows through it are part of a Grade II* listed historic landscape. Lancelot ‘Capability’ Brown was appointed to carry out the original landscaping in 1756, followed by Humphrey Repton into the early 19th century.  During World War II much of the park was ploughed and planted for arable use.

Case study date



~400 ha




Tarmac Ltd

Mineral Type

Sand and gravel

Habitat(s) Created

Standing open waters, Chalk river, Wet grassland

Restoration / Priority Habitats

Chalk river restoration
Wet grassland
Pond complex

Partnership Working

Hertfordshire County Council
Hertforshire & Middlesex Wildlife Trust
Environment Agency

Key Issues

Grade II* listed parkland setting
Continued collaboration

Public Benefits



Panshanger Park and the River Mimram that flows through it are part of a Grade II* listed historic landscape. Lancelot ‘Capability’ Brown was appointed to carry out the original landscaping in 1756, followed by Humphrey Repton into the early 19th century.  During World War II much of the park was ploughed and planted for arable use.

The landscaping within Panshanger Park supports over 950 veteran trees, with some thought to be about 1000 years old, and most notably the Panshanger Oak, known to be over 500 years old and the largest maiden (i.e. non-pollarded) oak in Britain, stands in the former Pleasure Gardens.

The River Mimram, which flows through water meadows at the site, is one of few remaining chalk streams in Hertfordshire to support important populations of wild brown trout & grayling. Chalk streams have become a rare habitat, with less than 200 chalk streams across the world, many of which are threatened by water abstraction, agricultural run-off , and channel modification.

Planning History

Panshanger House was demolished in 1954 and the parts of the estate have been worked for sand and gravel since 1959.  An application which covers the current mineral extraction was granted permission in the 1980s subject to a legal agreement between the then landowner Redland Aggregates (predecessor to Lafarge Tarmac) and Hertfordshire County Council. The wording of the agreement included: “to control certain aspects of the proposed development of the land, namely the preservation of the woodlands and wildlife, the management and development of the country park, and the establishment of a nature reserve”. Extraction at the site did not start until 1992.

The site was subject to a Review of Old Mineral Permissions (ROMP) in the 1990s, whereupon the extraction boundaries were amended thus protecting important areas of ancient woodland, veteran trees and other areas of ecological importance. The permission covers the extraction of 5.5 million tons of sand and gravel, equating to a land area of only 20-25% of the whole site.

Habitat Creation

Two mineral deposits are present at the site, a valley deposit following the course of the River Mimram, and then plateau deposits which rise up either side of the valley.

Worked plateau deposits that have been restored to agriculture, predominately for rye production, for Jordans Cereal, a brand that has signed up to use ingredients grown to Conservation Grade standards.  Additional features including supplementary woodland and hedgerow planting, and bird cover crops have also been incorporated into these areas.

Working alongside a number of organisations including the Wildlife Trust, worked valley deposits have been restored to a number of wetland features. In the far east of the site, a series of ponds of differing size and depth have been created providing an invertebrate haven, and already recorded to support at least 16 species of Odonata. A number of lakes have been created as part of the extraction process, which have been restored to a variety of end-uses to satisfy a number of differing stakeholder views. This includes a number of fishing lakes, a nature conservation lake which supports reed margins, and an island which is becoming a yearly stop off point for migrating osprey.

To prevent negative effects on the water chemistry during the extraction process, the River Mimram was diverted during the mid 2000s. During the landscaping of the Park by Capability Brown in the 18th century, the watercourse was modified to create two lakes within the site. As part of the restoration, the then Lafarge Tarmac re-engineered the river adjacent to these lakes, creating a new channel and restoring the characteristics of the river prior to changes undertaken in the 18thcentury. The River Mimram diversion was opened in 2005, with ‘full flow’ reached in 2013. The works were carried out in full consultation with the Environment Agency and include features such as meanders, riffles, pools, and the use of dead wood to provide shelter and changes in water flow speed.  There is a chalky base to the created channel with gravel spread along the bottom, which also mimics the reaches of the Mimram upstream at Tewinbury Farm.  Vegetation has been left to recolonise naturally, with management on rapidly colonising alder and willow already being undertaken during the winter season. The river channel restoration is now used by the Environment Agency as a best-practice demonstration site.

The watercourse provides habitat for water vole, already recorded in the area, and otter – a species known to inhabit the wider local area. To further increase the suitability of the site for water vole, the latest phase of working is being restored to seasonally wet grassland, incorporating a number of ditches and small ponds, along with appropriate bankside vegetation. In order to ensure the viability of water vole population at the site, mink control has been delivered by the operator’s gamekeeper.

While the veteran trees, and mix of woodland and wetland habitats, provide suitable roosting and foraging habitats for bats, the remnants of the former Panshanger Park house are also providing roosting opportunities. Several species are known to be utilising the foundations of the former orangery, and the former Ice House has been turned into a ‘bat cave’ with additional hanging features. Natterer’s and Brown long eared bats have been recorded hibernating in the bat cave.

Long-term Management

Decisions on the restoration and management of the site are made through the Panshanger Restoration Committee which consists of representatives from Hertfordshire & Middlesex Wildlife Trust, Hertfordshire County Council, Environment Agency and Tarmac. The original management plan was designed to create and manage the whole park for a variety of habitats, including land than has not, and never will be, worked for mineral. The committee meets on a quarterly basis to discuss the progress of restoration, aftercare and the wider management of the site, and is currently rewriting the existing 1982 management plan to address matters such as public access to the park, heritage and biodiversity.

Public Benefits

The approved restoration includes the provision of a ‘country park’, providing an area of new public open space to the residents of nearby Hertford and Welwyn Garden City. The size of the site, and the location of workable deposits within it, has meant that public access has been restricted until fairly recently. The site is still an active quarry and will remain so for about 2½ years (at time of writing) – within restoration taking at least a further 3 years (after planning permission has been granted).  However, operations are now geographically restricted, enabling a number of permissive routes to be opened up to the public within the eastern part of the site. Along these permissive pathways, interpretation boards have been installed, providing information on the different features at the site, including the Osprey Lake.  Historically, only two footpaths were present across the Park but under the final restoration scheme, 2.3km of pathways will be open to the public, providing a significantly greater public provision over the original situation. In addition, there is an aspiration to open a new visitor centre and associated infrastructure, a resource that is currently lacking in Hertfordshire.

The information set out within this advisory sheet in no way constitutes legal or regulatory advice and is based on circumstances and facts as they existed at the time Nature After Minerals compiled this document. Should there be a change in circumstances or facts, then this may adversely affect any  recommendations, opinions or findings contained within this document