During the decades after World War II, countries began shifting taxation from income to consumption. This shift has been associated with an expanding welfare state and left-wing dominance. However, the pattern is far from uniform and while some left-wing governments indeed expanded consumption taxation, others did not. This paper seeks to explain why, by exploring how experts influenced post-war tax policy in Britain and Sweden. Experts influence is crucial when explaining how the left began to see consumption tax not as a threat but as an opportunity. Interestingly, the influence of experts such as Nicholas Kaldor in Britain was different from the impact of Swedish experts (e.g. Gösta Rehn). I make the argument that the impact of expert advice is contingent on the political risks facing governments. The low risks facing the Swedish Left made it more amenable to the advantages of broad-based sales taxes, while the high-risk environment in Britain made Labour reject these ideas.