The economic constitution of the European Single Market is the result of compromise and bargaining, which will continue in the future. Therein, the BREXIT vote reflects a divergence of visions on scope and depth. Such divergences are not new. Going beyond the problem solving focus of current discourses around BREXIT, this study chooses a perspective from within the process of European economic integration. Focussing on desired outcomes rather than form, it sketches out underlying institutional issues and paths towards a legally enshrined variable geometry of participation in the Single Market. It also clarifies, why free trade agreements, even the most 'deep and comprehensive', cannot substitute economic integration. An innovative perspective on one of the most complex and fascinating current issues in International Economic Law.