I went for the first round of interview at McKinsey London after passing through my PST. The interview process was very standard as what was described on their website. My first interviewer was a very likeable lady with whom I had a very pleasant chat about my personal experience. The first case went well as well. Was a rather standard case about a prepared food company trying to gain larger market share. I stumbled over a Maths question mostly because I was a bit intimidated by the table who was arranged in a slightly unusual way. My interviewer gave me a little hint which helped me through that question. In her feedback she mentioned that I did well for the first case, so I guess it is okay to make minor mistakes. The second interview was not as ideal. The interviewer seemed a bit not interested in whatever i was saying even though she tried hard to not look away. I tried to engage her in the conversation and the PI part ended okay. Sadly I did not do very well for the second case- my structure was a bit messed up- as a result of my lack of practice of cases- would advise everyone applying for McKinsey/consulting practicing lots of cases with your friends so you feel at ease at the real thing. Their feedback was really helpful though. My first interviewer called to give me a very detailed summary of my performance and told me how I should proceed from here.