I'm an alumnus of St Andrews and LSE...studied IR a both institutions. Some of the posts on this thread are helpful and others are way off. Both are very strong in History; both are amongst the top 4 places in the UK to study IR. Much of your decision will come down to where you want to specialize. If you're focused on theory or international political economy, then go to LSE. If you want to specialize in international security, go to St Andrews. Both are very cosmopolitan, as St Andrews has a higher percentage of international students than nearly all other UK universities and LSE is one of the most diverse universities in the world. I would say they enjoy roughly equal prestige, depending on who you ask. In the US, St Andrews, LSE, Oxford, and Cambridge are viewed by many as in the same bracket of prestige. On the other hand, in parts of Asia LSE dominates and St Andrews is somewhat less well know. At both there is a clear focus on academic excellence, but the settings are very different. Think of St Andrews as a very small Scottish version of Oxbridge with all the balls, formal dinners, ancient buildings, gowns, and various other quirky traditions that entails. The LSE is more like a very large think tank in the heart of London. Outside of class people are exploring London to the fullest and many take up internships...at the LSE people appear to be more overtly driven by career goals. I hope this helps.