15 minute initial online test before being invited to sit tests at their Edinburgh offices. Pretty gruelling day of testing and interviewing. You sit several written tests including 2 larger problem solving ones which others have alluded to in their reviews (essentially travelling salesman problem and designing a card game). You get interviewed on those two main problems about why you did certain things and how you could improve. After that the interviewer whipped out my CV and rapid fired a coupe of specific questions at me, I think to see how well you handle pressure. They said I would hear within a week but it took several weeks and a couple of follow up emails before I got feedback, which was quite detailed and polite once I did get it.