The union of England and Scotland was the subject of a wide range of theoretical and conceptual analysis both in 1603 as well as between 1700 and 1707. One part of this analysis took place in the British Isles and used the Spanish monarchy as a model. This article attempt s to describe how both parties perceived each other and focuses on the different ways in which their members were brought together, how they related to each other and the ideas they had on belonging to the whole. It also looks at the contributions of commentators like Alberico Gentili and Arthur Duck, who have not to date received sufficient attention.