Is it a policy to send redacted versions with obvious redaction such as blacked out information, headers, etc? Does an un-redacted sensitive document have "un-redacted, sensitive" label on the top? It's not always obvious what might be considered sensitive. The police would know better than some local council members in their first term. If you get a document with a load of recipients or CC's, you might not think that keeping mum is in order.
I do agree that the council probably didn't need to see the document. They may have only needed to know that it exists, the type of information that it contains and that it can be viewed at the police station or by special application.