This paper examines the characteristics of the collaborations between inventors in the United Kingdom (UK) by looking at what types of proximities – geographic, organisational, cognitive, social, and cultural-ethnic – between inventors are prevalent in partnerships that ultimately lead to technological progress. Using a new panel of UK inventors this paper provides an analysis of associations between these ‘proximities’ and co-patenting. The results show that while collaboration within firms, research centres and universities remains crucial, external networks of inventors are key feature of innovation teams. The analysis shows that external networks are highly dependent on previous social connections, but are generally unconstrained by cul...