BAE use competency based interviews, plus the usual walk through of your cv and questions about the role on offer. Competency based questions are all about describing specific situations from your career, what *you* did, and what the result was. Often they want to know what you learned, and will ask for negative outcomes as well as positive ones. You need to be prepared - think about a number of actual cases where you can describe clearly what you did that demonstrated key competencies such as leadership, developing others, or team work.