Eurosceptic argument - as it was - held together rather well around a single unifying idea: that the UK could not historically, culturally, spiritually, politically go where the EU is heading....to (crudely) "a country called Europe".
Britain's opt-outs and exceptions were testament to that fact.
'Brexitism' then grew out of euroscepticism in the 2000s because of the feeling that despite opt-outs, the integrationist ratchet was still dragging us where we didn't want to go. /2
Yet the eurosceptic movement (as it was still called), still roughly held together despite the narcissism of small differences. /3