A London gin maker has stepped in to help protect North Wiltshire’s largest juniper population on the Calstone and Cherhill Downs.

No 3 London Dry Gin has given £1,000 to pay for a 150-metre-long fenced enclosure to protect seedlings on the National Trust land, which is also a Site of Special Scientific Interest.

The plants, which produce small, dark, purple berries that are the essence of gin, are in decline across Wiltshire and the UK as a whole because of excessive grazing and a lack of habitat for young plants.

They are also under threat from a new deadly disease named phytophthora austocedrae, which infects the plant through the root system and kills off any foliage.

On the Calstone and Cherhill Downs the plants can be found in two areas, with 500 plants on the eastern side of the site and only 60 plants struggling to grow on the western side.

Keith Steggall, a countryside ranger for the National Trust, has been looking after the area for eight years and said the new enclosure had helped to protect seedlings from cattle grazing nearby.

He said: “As well as being an important species in its own right, it’s important for other species as well. There’s the juniper shield bug, which relies on juniper, and there’s other insects as well.

“We have two areas of juniper, one is doing pretty well and one is struggling because cattle are going in and damaging it and it is struggling to get any seedlings going.

“The fencing was something we were going to do anyway, but getting the grant will enable us to get the work done this year instead of trying to find other ways of financing the work.”

The gin company gave its grant through Plantlife, the UK’s leading wild plant charity, which aims to protect wild plants and build an understanding of how they affect people’s lives.

Tim Wilkins, species recovery coordinator at Plantlife, said: “Juniper has been steadily declining over the last few decades and without action now, it actually faces extinction across Wiltshire and much of lowland England within 50 years.

“That would represent more than the loss of a single plant type as it supports more than 40 species of insect and fungus that cannot survive without it. We’re absolutely thrilled that No.3 is bolstering our efforts in these ways.”

Mike Mackenzie, of No.3, said: “Juniper is very much at the heart of No.3, so it’s entirely appropriate that we support PlantlIfe’s activities in these ways. We’re hopeful of healthy days ahead for Wiltshire’s juniper.”