If I try to restrict Space permissions available to the `Anonymous' user to `View' only, the edit tab disappears for all usersregardless of theor permissions.

If I enable `Create' permission for the Anonymous users, then the Edit tab appears.

I can still edit a page by changing the url, if I click on the info tab it's a url
like:

http://www.foo.com/wiki/pages/pageinfo.action?pageId=257

change "pageinfo" to "editpage":

http://www.foo.com/wiki/pages/editpage.action?pageId=257

So it let's you do it, it just doesn't show the tab.

Attached is the permissions