Fairly in depth - about 5 rounds including case study presentation to the head of the business. The case study was ambiguiously strucutred so I ended up spending a substantial amount of time on it. If I were to do it again, I'd keep it simple and focus on getting your key points across with strong presentation skills.

Technical round of interview with subject oriented questions. Economics, Statistics, Mathematics and Econometrics. Modelling techniques, Project overview. Some questions on tools and technologies were also there. Business case studies, Quantitative Analytics.

Phone call then meet up for breakfast and then a case study. Wasted a lot of time with very little to offer in return. Was first headhunted then rejected due to a lack of experience (which I was told not definitive during first call). Was impressed by my case study response but at the end of it not right with no substantial reason.