The five main 'winners' of WWII are the permanent seats on the UN security council... things have changed since then, but you probably will find that the five of the top ten biggest weapons manufacturing nations are the same permanent members... if not the top five.

So the UN is a reflection of the world situation 60 years ago... of all the populations lest represented it would have to be non-Europeans like India, Africa and Middle East. India has to be the most compelling to be a permanent seat... was on the winning side in WWII, is a democracy, has the second largest population in the world, is a nuclear power...