Thank you Sebastian - a timely comment, as I just downloaded and tried this in the Pro edition to see if it was different, but it made no difference.

So is it right that there are TWO obstacles here: 1) page edit permissions override module edit permissions (?), and 2) users with the built-in "Administrator" role have overriding full control permission of everything, ignoring the permissions grid?!  If so, both seem very inflexible design decisions.

If #2 is the case as you suggest, I presume I must remove the Administrator role from users I wish to limit, and grant them a less powerful admin role. If I do this, however, is it possible to automatically grant this less powerful admin role with edit rights to newly created pages? Otherwise this isn't a solution, as such admins would be unable to add new pages.

Many thanks,  Ben