You say "tree warden."
What is it you actually mean?
Is this a local role established and filled by your council or is it the UK Tree Council Tree Warden scheme?
If the latter, whilst a person usually (not always) has to have a parish, town or county council endorsement to become a UK Tree Council Tree Warden, once accredited, the function, terms and conditions etc are entirely UKTC rather than local council.
You can perfectly reasonably have a UKTC Tree Warden who has absolutely no affiliation, line of functional authority or even contact with a parish, town or county council. A parish, town or county council has no authority to task, assess, direct or censure a UKTC Tree Warden - they are entirely separate entities.
The part of DBWs post which IS correct is that the issue lies more appropriately in examining the conduct of the clerk and the grounds manager in the execution of what has been stated as essentially a member of the public tasking them...