Prior to the interview most of the advice I was given was centered around generic questioning such as; Why do you want to do a PhD, why here, what do you think are the gaps in the field currently etc which it was helpful to prepare but the actual interview was focused far more around my understanding of research principles ie blinding, randomisation, bias and then previous research experience (specifically certain details to check my understanding as opposed to me just telling them a rough synopsis) and lastly a large bulk was discussing my previously submitted proposal (which was asked for attached to cover letter and CV submitted at application stage). I was interviewed by the potential supervisor and college principle who were both lovely and made me feel at ease. I didn't think the interview went too well when I came out but I think I was just being hard on myself! I was able to answer everything, show I was keen and at least consider if not counteract their critique specific to my proposed idea. The interview was around 25 minutes in total (I think they were on a tight schedule getting all the interviewees through) and I found out I had been successful the same day.