Local volunteers are leading a restoration project above Shoreham to reverse decades of ecological decline and revive butterfly and wildflower populations.
Mill Hill: restoring a precious chalk grassland
A community-led effort is underway to bring Mill Hill Local Nature Reserve back to life. Once world-famous for its butterflies and wildflowers, the site has suffered decades of ecological decline — but now, local volunteers are stepping in to help.
Beginning in October, this rare pocket of Chalk grassland will be the focus of urgent conservation action led by local resident Jonathan Crawford in partnership with South Downs National Park Authority and the conservation volunteers of Greening Old Shoreham.
What’s happening – and when
Volunteer work parties are scheduled for 2, 9 and 14 October, marking the start of a long-term effort to reverse decades of decline. Local volunteers will help remove invasive shrubs on the steep slopes—particularly cotoneaster and wild privet—while contractors use machinery on more accessible overgrown sections.
The volunteers and the machinery will be further aided by 65 Herdwick sheep. Arriving in late September to graze the slopes and help control regrowth naturally. Trained volunteer ‘lookerers’ will monitor the flock and ensure their welfare as part of an ongoing conservation programme.
The goal is to restore open grassland conditions needed for native wildflowers and butterflies to thrive again.
Why it matters
Mill Hill is a 33-acre remnant of what was once a 724-acre sweep of chalk downland, gifted to the council in 1934. Known in the 19th century as ‘Shoreham Bank’, it was internationally renowned among butterfly enthusiasts for its enormous populations of Chalkhill and Adonis Blue butterflies.
Today, those numbers have collapsed. In 2023, only 47 Chalkhill Blues were recorded on the site’s main transect. The iconic spring bloom of horseshoe vetch, essential to the butterflies’ life cycle, was almost entirely absent this year—likely for the first time in living memory.
How we got here
Mill Hill’s decline has been slow but steady. The chalk grassland depends on low-intensity grazing to stay open. But after WWII, modern farming practices, the spread of myxomatosis and rabbit haemorrhagic disease (RHD) wiped out local rabbit populations—once key to keeping scrub at bay.
Now, aggressive species like cotoneaster and wild privet are rapidly taking over. Cotoneaster, in particular, thrives in dry, sunny slopes and resists natural grazing. Both species are toxic to livestock and crowd out native plants.
How to help
Mill Hill’s recovery depends on local people. Whether you’re up for scrub clearance, wildlife recording, or helping with sheep grazing, your time and energy can help bring back this rare habitat and protect its remarkable biodiversity.
To get involved, email Greening Old Shoreham or contact Jonathan Crawford at jc@tgsi.net.
Mill Hill Nature Reserve, Old Shoreham, West Sussex
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