Who should elect a national government?

Migration Watch UK wants Commonwealth citizens removed from the UK franchise restricting it to British citizens and to the citizens of the Republic of Ireland and the small number of Commonwealth countries that provide reciprocal voting rights. They argue this group accounts for nearly a million voters, large enough to effect an election result. Iain Dale wants to go further and bring the Irish into line with other EU citizens and remove the right from Irish citizens resident in the UK to vote in a general election (regardless of the reciprocal arrangements).