While devolution in Scotland and Wales is often established as the settled will, it has been built on unsettled ground, lacking a robust system of intergovernmental relations, and sitting increasingly at odds with the central principle of parliamentary sovereignty. Examining successive UK Conservative-led governments, we evaluate devolution in Scotland and Wales through the lens of the Asymmetric Power Model and the British Political Tradition, documenting changes in the position of successive Conservative governments, from the more plurinationally sensitive respect agenda of David Cameron to the more assertive and intrusive Unionism advanced under those in post after 2016, notably Theresa May and Boris Johnson.