Hi All,
I just wanted to include some final thoughts for future applicants lurking on this forum after making it through the process myself. Keep in mind that the Trust emphasizes not just leadership, but social leadership (http://lexicon.ft.com/Term?term=social-leader)-- took me a while to realize this. I will go ahead and echo previous advice on this forum and say that, for the interview, my experience closely mirrored the info provided on the website-- so do practice with the outline they provide. They really make an effort to lead a pleasant discussion, rather than asking a series of questions or trying to grill you, so go in ready to bounce off their energy and share your research and the importance of your field. Don't spend too much time preparing for ethics-based questions (a mistake that I made, as my field is one that is riddled with ethical dilemmas, but I didn't get a single ethics question...n=1, but take that as you will). In retrospect, once you make it to the interview stage, I would say they are most interested in determining your "fit" with Cambridge (i.e. what have you done, how will that carry over to your time there) and the goals of the Gates scholarship (mostly social leadership). Of course, this all takes years to build, and if you've made it this far, you've certainly "checked the right boxes"! Just be yourself and keep these overarching goals of the interview in mind when answering questions.
Lastly, I just want to say that we are often our own worst critics. I almost stopped myself (so many times!) from submitting an application because I didn't think I stood a chance! No one from my (large) school had ever gotten it before, so why waste time that I could be putting towards something productive? Please don't let these thoughts stop you. Wish you all the very best!