The investigation by law firm Bevan Brittan had initially been expected to be completed by May but is still ongoing.
It follows a complaint from street tree campaigner and Freedom of Information (FOI) expert Marcus Combie to the council in relation to its use of legal privilege in emails and FoI.
Bevan Brittan was commissioned by the council to investigate whether the attempted use of legal privilege to stop emails entering the public domain via Freedom of Information requests was applied properly after senior officials marked messages about the tree-felling programme as “not subject to FoI”. The council - which has already previously admitted some emails were "incorrectly marked" in this way - has previously said the law firm will provide recommendations on "best practice" to feed into its complaints procedure.
Councillor Julie Grocutt, deputy leader at Sheffield City Council, said: “Unfortunately, due to the scope of the enquiry and the volume of documents involved it has taken longer than anticipated to identify and provide all the required information to Bevan Brittan. Despite this, progress has been made in reviewing materials and conducting interviews as part of this investigation.
“We are confident that all information has now either been sent or is in the process of being identified, to enable the investigation to conclude as soon as possible.”
Coun Grocutt said over £15,000 has been spent on the investigation to date, with the final cost expected to be in the region of £25,000.
“We can confirm that the costs associated with the investigation being conducted by Bevan Brittan, to date, are £15,718,” she said. “This is within the initial estimate that costs might be up to £24,700. Once the investigation has concluded, a report will be sent to the complainant directly and the findings will also be used internally to identify any service improvements required.”
Emails involving senior council officers about Operation Quito - a major police operation supporting the council’s street tree-felling operations in early 2018 in light of increasing protests against the policy - were released to Mr Combie in late 2019.
Several of them were given the subject line ‘Covered by legal privilege and not subject to FOI’ and largely related to the council’s involvement in a shared media strategy with South Yorkshire Police and a wish not to publicise it for fear of ‘politicising’ the force’s operation.
In July, it was revealed that the Information Commissioner’s Office had opened its own separate investigation into the practice following a complaint by a member of the public in April.
The city’s tree-felling saga saw thousands of street trees felled and replaced with saplings as part of a £2bn highways management contract with Amey. Campaigners argued many of the tree fellings had involved healthy trees and had been unnecessary.
The increasingly-bitter dispute reached its height in early 2018 with Operation Quito, which saw dozens of police officers and private security guards accompany daily felling operations in the wake of growing protests. The council has since changed course and adopted a strategy designed to save more trees.
In October last year, the council was ordered to apologise to the people of the city after a damning Ombudsman report found it had misled the public, misrepresented expert advice and acted with a "lack of honesty" over the course of the saga.