The process took 4 weeks. I interviewed at Three (Dublin, Dublin)
Interview
Completed an online assessment form with the usual details and an attached CV.
Few weeks later got a call from the head of the program for a short phone interview. Mainly compentency based questions. About a week later I got a call asking if I could attend an assessment day a week later, so I went.
Day consisted of a group ice breaker, a group exercise/discussion. Then later you were given a chance to do a 15 minute presentation (which you decide yourself based on a brief you get emailed before the day). Then there was a 1-to-1 interview with a very pleasant woman. Then a tour.
Overall, everyone was super friendly and answered any questions. I enjoyed the experience and would recommend Three.