Does Britain want to be a self governing country or a vassal of a foreign power? We've spent 1000 years defending the former so I think it would be self evident why this is necessary.
Too much sovereignty has been given away to the unelected in Brussels. I don't see why we should bow down to laws made by unelected commssioners, which are rubber-stamped without proper scrutiny. I am not some little Englander, and I understand the need for peace in Europe of course but this has gone quite far enough. They are destroying the essence of each nation and burdening us and our businesses with unnecessary paperwork and laws, and that friends is a bigger crime.
Sovereignty needs to be reaffrimed in an amended 1971 EEC Act as being held supremely by the UK people and that the UK parliament is ultimately in control of all law making in this land. Note the 1668/9 Bill of Rights already says this (this is a treaty between Monarch and people and cannot be merely repealed by Parliament by the way).