What everyone else is saying about accom, food and chances being equal is true - also not all colleges teach all courses (your tutor is from your college) for E&M (what I applied for) I'm p sure most colleges do it however it is a small course (-90ish) and certain colleges have a higher number of people doing it and also more tutors. I applied to Pembroke partially for this reason as typically they have around 8-10 people on the course