The hiring process was quite quick - I had an interview scheduled within a couple of weeks of applying. Normally they do two separate ones (for HR and the specific department), but mine they combined into one (with two people interviewing me). I got through to the second round, which was a psychometric test (personality and mathematical/language aptitude) and I took that a week later. From memory there were four sections and the whole thing took about four hours to complete, but it was possible to take breaks in between. I was unsupervised - just me and a laptop in a small room.