I am asking a different question to the previous thread on the UK and the EU. As I understand it the EU is formed on binding international treaties. If the UK is trying to renegotiate terms the whole community is entitled to renegotiate those treaties and we are looking at referenda for years to come. Equally, the membership could take the line that these are signed up to and the only option for the UK is the exit door. What mechanism allows Cameron to think a renegotiation is possible?