Selecting Do not allow for the system preference OpacAuthorities does hide the Authority Search tab on the Simple Search page but authority searches remain possible on the Advanced Search page by selecting More options to expose Subject and Author searches. The description of the system preference should explain that the change to the preference affects the Simple Search page only.
The options on the advanced search for subject and author search in the bibliographic data by text and not in any authority data. They are completely independent of using authorities. Unless we are talking about different things?
Oh, thanks. I raised this ticket wrongly as I was not aware the Advanced search works on the headings in the biblios, not on the authorities. Sorry! I will mark this one as BLOCKED to get rid of it.