Grant Thornton came to my university campus to give an information session and I received an interview after applying online. My interview lasted about 40 minutes. I was interviewed by two people, one audit manager and one talent acquistion manager. The interview questions themselves were mostly behavioural and were pretty common. For example, I was asked to tell them about myself and also to name my proudest achievement. However, only about 5 questions were actually asked which took up less than half of the 40 minutes. I was asked to begin asking GT questions instead. Unfortunately, I didn't prepare quite enough questions and soon ran out of them. My advice would be to prepare more on this area.