Great, thanks for this Helen. I could indeed set the RSS and override permissions from the Updating Forum page, so all is now well.
For others' info, I did find, that the 'Older discussions' link was missing from the page, until there were 10 postings (can this setting be reduced anywhere?), but i was able to get to the Updating Forum page anyway with the URL: ...../moodle/mod/forum/view.php?f=1165&showall=1165 where 1165 is the forum ID.
Thanks, Tony