It is the second-best place for nightingales in the country, a sanctuary for rare barbastelle bats and home to nearly 1,500 invertebrate species, including a quarter of all Britain’s spider species. But Middlewick Ranges on the edge of Colchester is poised to be sold by the Ministry of Defence for 1,000 new homes.

Conservation scientists have written to the UK defence secretary, John Healey, urging him to reverse the decision to sell the 76-hectare (187.8-acre) site for housing. Experts who have fought the proposals for eight years say the house-building is based on faulty and flawed environmental evidence and must be reversed.

A freedom of information request by campaigners has revealed an ecological report that in 2017 identified large swaths of rare acid grassland at Middlewick, which has been untouched by a plough for at least 200 years and contains more than 10% of Essex’s remaining acid grassland.