The overall process took 2 months. There are 3 stages:
1. Online application, no need to include cover letter
2. Online video interview, you are requested to record answers to a set of questions. Good news is that you see the question first then you can practice as many times as you want before submitting the answer. So no need to prepare too much beforehand. Since you can literally searching info before recording.
3. Selected candidates are invited to an assessment center. For the 2019 entry, they organised one AC in china and another one in Macclesfield for chinese students currently studying abroad. I went to the AC in Macclesfield, we are 8 in total. You will have group discussion, writing exercise, value-based interview, and individual presentation. It last 6 hours in total and it was not very demanding. Juries are very friendly. All costs will be reimbursed for you to attend the AC.