well I cheated a bit ...
I first chose 'advanced search' from the search drop down. Then I searched for 'comune' using the 'search title only' option, searching all open forums (with "child forums" checked too) and specified results to be ordered by relevance and shown as threads (not posts) which limits the number of results to a more manageable amount. That only gave a few results (and not the one Chris wanted).
I happened to remember that Marc had been involved in that thread, so I repeated the same search but this time I also entered Marc into the user field (with 'excact match' checked) but all other criteria as before.
That gave no results at all, so I then changed from 'search titles only' to 'search entire posts' - which returned quite a few threads, but the one we were looking for was on the first page of results.
so, basically it's a pile of pants & doesn't at all do what it says on the tin, as the word 'comune' WAS in the title but it wasn't returned by a 'search titles only' search.
NOTE however that in this case a google search would have worked (if Chris had spelled comune correctly with one 'm' instead of two ... albeit it returned a link to the archive rather than the live forum:
site:italymag.co.uk "a tale of two comunes" - Google Search
.. .and entering "tale of two comunes" in the google search on the site returned the thread as its 3rd result.