Thanks for the suggestion Davide, I’ve not tried it though as you were unsure of the consequences and I didn’t want to break things!
I think I’ve found a better way though. On a Windows PC I installed RSAT, which (among other things) lets me do all the things I need to do to administer Active Directory settings. Using RSAT I can get in there and add users to the admin group and do other nice things like force a password reset on next login etc. Basically it appears to have the same functionality as using the ‘Manage Active Directory Users and Groups’ option on Windows server 2003.
Download RSAT here: https://www.microsoft.com/en-gb/download/details.aspx?id=45520
Setup guide here: https://www.itsupportguides.com/windows-7/windows-7-how-to-install-the-active-directory-users-and-computers-tools/
I have another query relating to this method though. If I add a new user via RSAT then look at the user in ‘Users and Groups’ on NS there is a key shaped icon next to the user name. It appears I can still edit the user (it doesn’t appear to be locked as the key would indicate). Any idea what the key icon signifies?
Thanks again.