...

Conversely if you go to http://www.tertius.net.au/mailman/admin/ the link back to the regular overview page points to /listinfo instead of /mailman/listinfo

Yes, your web_page_url attribute doesn't end in a slash. This is a known problem which should be fixed were you to upgrade. In lieu of that, make sure all your list's web_page_url attributes end in a slash.

I'm having the same problem and, as far as I can tell, my web_page_url attributes do end in a slash. Specifically, the Base URL (last item) on the admin page for the list is listed as: http://javamlm.mills.edu/mailman/. The following appears in Default.py:

DEFAULT_URL = 'http://javamlm.mills.edu/mailman/'

I'd be grateful for any clue as to what else I should check, or what I've got wrong.

Ellen