We have a much bigger share of the vote (in both legislatures but obviously in the Parliament politics comes into it a lot more) than the majority of countries (I think we are joint second with France after Germany who has the biggest population). That means the UK's voice is heard louder the most other countries and naturally we have a bigger say in the laws that are passed. Also, if we team up with France and Germany on a partiulcar issue it's very hard for anyone else to get their own way (good for us, bad for them)