Hello,
Politics of the International Economy is a new degree that King's is starting this coming academic year, which I (luckily, I believe!) have been accepted to and have firmed. I've been to a post-offer open day, so I can tell you the (likely) minimal amount of what I know, but I'll try not to run you over with the King's propaganda machine.
Ok, so PIE, what is PIE?
Politics of the International Economy - it's basically the study of "political economy", which is distinct from pure economics in that it is studying the political, legal, international, sociological impacts of economic output/input within countries and nations and states and organisations, and it is distinct from pure politics in that you are studying politics bearing economics heavily in mind. Now, international political economy is just political economy.. but on an international level.
What is PIE at King's?
PIE at King's can take two routes, that is to say, you can get a B.Sc or a B.A, and the difference between these basically relies on the modules you take in second and third year. For the B.Sc, you can take some heavy duty economics modules, including full term-length courses in macro and micro economics, econometrics, etc.. this route prepares you for studying economics or economics-based subjects at graduate level. (if you look online at some MPP/MPA courses in the world, or even some specific politics and international relations postgrad courses, they rely a uni-level foundation in econometrics, macro and micro and quantitative, so evidently this course is going to sit perfectly for the requirements for these courses). If you take the B.A route, you are basically following the curriculum of the "international politics" B.A students, with a few political economy related subjects that are necessary, however you have far more room to take subjects from other departments, if that's your thing.
Political economy is quite a niche subject, and many universities which offer politics and economics respectively don't cover more than a module on it, if that, however at postgraduate level, it's an extremely wide and varied subject, with many opportunities to study specifically that at some big-name institutions.
I guess in essence it's going to make you a pretty rounded student too, as the necessary scientific and research methods covered in the economic and quantitative political analysis lessons are going to complement the theoretical political aspects of the course, and make you a student that has studied a scientific and theoretical "arts" subject at uni. I think this is a pretty winning combo, personally.
I hope this has put you in the know a little more, and lastly, isn't saying that you're studying "pie" at university pretty damn cool?
Let me know if you have any more questions and I'll do my best to answer!