There are such things as inalienable rights Yorkie. In terms of so called acquired rights gained through residence in another country - basically the longer the residence, the more rights you have. These are established in the Vienna Convention, which Britain is signatory to. The government may huff and puff about what rights to grant to those EU. citizens, and may try to appear generous, but the truth is that a lot of these acquired rights are guaranteed by International laws and conventions which are independent of the EU. A person cannot be stripped of citizenship in this way - the question now is to look at the substance of EU Citizenship to see if it was/is over and above that of national citizenship. Initial indications suggest that this cannot be taken away by the actions of individual national governments - and that EU Citizenship would actually survive independently for the individual citizen. The situation is not completely clear and is being worked on by both the ECJ and the European Court of Human Rights. If a British citizen refused to give up EU. citizenship and actually takes it to an international court then it could be a very tricky case - but, as always, the 'individual' often doesn't have the financial resources for this step, and the reality is often different to theory.