I am heartbroken to write these lines about Weihan. He was warm, generous, and funny. PhD end of term drinks and Fridays at the George pub would always be better if Weihan was around. He would organise dinners at Chinese restaurants across London for our class or invite us to food and drinks on his terrace in summer when he lived in Stratford. We visited Claudio together in Switzerland to ski and fought over the best meat on the Raclette grill during dinners. I have learned a lot through the many discussions with him from topics in economics to global politics, history, or science, and I wish there could be many more. Weihan was also impressively smart and hard working. I could only marvel at the incredibly high grade he achieved in our first year econometrics exam. He used to say "This is just because I have trained taking exams a lot when I was younger, you would have achieved the same" and we both knew this was not true. We also both liked mathematics for its own sake and at some point later in our PhD decided to study some topics in maths. The speed with which he understood the problems, could draw them out on a whiteboard, and his ability and interest in the subject were remarkable. He loved learning and developing his ideas in research, and his chance to share all these ideas with others was tragically cut short. I and many others will tremendously miss a sunny, brilliant and affectionate friend. Most severely, his wife Leyi, son Yilun, his parents, and wider family will have to live without him. I wish them all the strength possible. Weihan will always remain in the thoughts of all the people who knew him, the ways in which he influenced them, and in the stories they tell about him. Rest in peace my friend.