One of London's oldest parks is today welcoming a herd of rare cows which haven't been at the site for over 150 years, writes William Janes.

The new herd of long horn cattle were let out to graze on Wanstead Park, east London, on Thursday, September 17 to help maintain rare acid grasslands.

The habitat, which is now threatened and exists only in scattered patches around the capital, supports a wide range of rare and beautiful plants and animals including insects and spiders.

It is also home to a variety of butterflies including small heath, small copper, and common blue.

These species like the hot ground conditions in the summer and autumn and rely on plant life and seasonal cycles unique to acid grassland.

The park lies on the fringes of Epping Forest, where the cattle have been grazing for the last 1,000 years.

The reintroduction of cattle marks the start of The City of London Corporation's two-month trial across September and October to help conserve the species that live on the grade-II listed park.

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Graeme Doshi-Smith, chairman of the City of London Corporation's Epping Forest and Commons Committee, said: "Our grazing pilot is helping us identify better ways to protect Wanstead Park's historic views at the same time as conserving a wide range of species and supporting an even better ecological balance at the site.

"Grazing is used as a natural way to manage grasslands and meadows across Epping Forest.

"As part of the programme we have prevented encroachment by scrub and more vigorous grasses in favour or rarer plants and herbs, benefitting a whole range of insects and birds.

"It is exciting to be grazing heritage cattle here in this East London park, right on the edge of our capital city."

The habitat is under threat from advancing scrubland and could be lost if it isn't properly managed.

To avoid having to use unattractive electric fences, the cattle will be stopped from wandering too far by a GPS collar system that creates an audio signals when the animals cross an invisible boundary.

While conservationists hope that visitors will enjoy sharing the park with the cows, they ask that people avoid feeding or approaching them.