[microtonal]

Your linked page says that Britain had four opt-outs before they left the EU, more than any other country. At some point it even has five opt-outs.

Not sure if they had opt-outs immediately when they joined the union (as the grandparent claims). But they were surely the member for which most exceptions were made.

Some non-Brits were actually happy when Britain left the EU, since it removed a member that frequently blocked or slowed down integration. Not sure whether this is true though.