I was contacted via a recruitment consultant, I then submitted my CV and had a follow up phone screen with a category leader. This was mainly focussed on questions based on my current experience and CV. The next step was to complete verbal and numerical reasoning tests online. I then had two rounds of interview loops at Amazon, meeting people from different functions and going through competency based questions. At the last session I was also asked to bring along and discuss a short written exercise. It was a long process but I felt I had a good understanding of the company and the people by the time I was offered the job - I think if I hadn't been really interested in the opportunity I would probably not have kept going back for the interviews though as I had to spend 3-4 hours at a time in the Slough offices for the interview loops.