Thanks Gavin and Arnie,
I'd actually spotted the authentication page in the wiki, but since what we'll use is CAS authentication, and that is listed as "under development" and down atthe bottom it says "The method
check_casis in the Authen module, available here soon" I'm sort of unclear about what version of WebWork this module is in.
We've got 2.4.5. Is check_cas in there, and working reasonably? Or is there a different version I want to be using for this purpose?