It should be law that anyone who does not reside permanently in the UK should be removed from the line of Succession. If someone chooses to live in another country for a sustained period of time, they should automatically forfeit their claim in the line of Succession.
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The succession to the throne is regulated by Parliament, with various conditions imposed on those who are able to be in the line of Succession. It is not right that someone who would choose to live abroad could also maintain a claim to the throne of the UK.