There are three things that Oxford tutors are looking for in an interview. All of these things have to come across naturally as they can see through if you are being disingenuous.
Passion for the subjectIf you have a natural and authentic interest for the subject, then this will shine through naturally. The best advice I was given to show this was to know a little about a lot and a lot about a little. Open MindednessOxford tutors are looking for students who are curious and hungry to learn more about their subject. The best way to show this is to demonstrate times when you've questioned your subject and seen issues from alternative perspectives.Interpersonal Skills It is important that the tutors will enjoy teaching you and that you'll be able to contribute to the small community that is an Oxford college. Show that you are humble yet quietly confident and view the interview as a chance to show the human element to your application.