"Let's start to have a grown up debate in this country about who we are and where we want to go and what kind of country we want to build"

In this quote, Ed Miliband is calling for a fully grown and major conversation about the identity and direction of our country. He thinks that it is time for us to move beyond petty arguments and participate in a thoughtful and efficient argument about our values, objectives, and the type of society we want to create. By using the expression "grown up debate," Miliband is highlighting the requirement for a rational and considerate exchange of ideas, rather than the divisive and frequently childish discourse that can dominate political conversations. He is urging us to come together and actively form the future of our nation.