I applied online. The process took 2 weeks. I interviewed at UK Border Agency (Heathrow, England) in Aug 2016
Interview
First, we were given a case and we had to write down our solutions. It lasted 15min. The case does not have clear-cut solutions but they want to see your creativity and approach to problem solving. Then, at the interview we had to discuss this case and our approach by two interviewers who asked pretty tough questions. That was additional 15min.
Interview questions [1]
Question 1
Then the rest 30min or so I spent answering the competency questions which were provided in advance: 1. Changing and Improving; 2. Delivering at Pace & 3. Collaborating and Partnering. The interviewers asked questions as they went along: anything unclear or why I did what I did and so forth. In short, prepare well for the grilling.