I applied online, got through the video interview and then was invited to the AC in London. There I had 3 interviews and one case study. There were two shifts with 15 people each.

The process consisted of two 30-minute on-campus interviews, followed by an on-site super day. From my experience, none of the questions they asked were too technical in nature. They were mainly behavioral, familiarity with Amex, and some consulting-style strategy questions