Thanks for the replies!
Yeah I wasn't worried, I just was wondering if having studied the field could encourage them to focus on asking more technical questions. I realise you have to be pin sharp and cover as many bases as possible.
I noticed a few people have said they were able to drive the interview to talk about things they wanted to, but how easy did you find that in practice? Were you able to just drop hints in your answers, or did you go all out and start a new topic on you own?
Thanks!