Police have been drafted in to help tree fellers do their work

The city of Sheffield planned to fell almost half the trees lining its streets, it has admitted after losing a battle to keep documents secret.

The revelation has injected new vigour into a campaign that has spent six fraught years fighting a project to replace mature trees, including cherries, lime trees and one of the country’s few remaining venerable elm trees, with saplings as part of a £2.2 billion plan to upgrade roads and pavements.

The council tried to withhold the information on how many of the 36,000 “highway trees” were under threat but was ordered to make its documents public by the Information Commissioner. Campaigners had previously obtained some details of its 25-year agreement with Amey, a private contractor, but passages about the number