For me, it was that the ECJ could overrule the UK parliament, the implications were too grandiose for the meagre 9.7% (and decreasing ever since the 1970s) rep

For me, it was that the ECJ could overrule the UK parliament, the implications were too grandiose for the meagre 9.7% (and decreasing ever since the 1970s) representation to represent. Simple as that.