Conduct the round of interviews at their London office (16 students invited to interview in that day's session. Head up to a room where you take a 20 min numerical test (probably just to check the extensive Numerical & Reasoning tests you have done beforehand to get to the stage of interview were your own work). Wait in that room with the other candidates chatting to them or preparing your thoughts for when you will be called for your half hour interview with one HR colleague and one person from the business. You run through your 5 min pre prepared presentation of 3 slides on a topic of your choosing after which they may ask you some questions on it before moving on to the competency questions. After your interview you are free to leave and they will normally call back by the end of the week to give you a decision