The Welsh Labour government occupies a unique position in UK territorial politics, favouring neither the status quo nor independence for Wales while advocating a new settlement for the whole state. This article provides a detailed examination of its policy, focusing on its position on the doctrine of parliamentary sovereignty. Drawing from a range of documentary sources, we analyse the Welsh government’s constitutional proposals and its decision-making in the wake of the 2016 referendum on European Union membership. We argue that Welsh policy is defined by ambiguity. While it advances an alternative constitutional vision, it refrains from rejecting Westminster’s sovereignty outright. In the aftermath of the referendum, it sought to accommod...