Infrastructure provides many direct benefits, but many more which are diffuse across the whole economy and society, and endure through time. Typically, infrastructure investments are appraised using conventional cost-benefit and multi-criteria analyses. In the UK, this includes the approach set out in HM Treasury’s Green Book[35] which is are often elaborated with specific guidance for individual infrastructure sectors, for example by the Department for Transport’s Webbased Transport Analysis Guidance[36] and the Environment Agency’s Flood and Coastal Defence Project Appraisal Guidance.[37] Standard economic approaches typically assume that individuals are rational, markets behave in an efficient fashion and environmental, demographic and other socioeconomic factors are stationary. It is inevitable therefore that existing approaches only partially assess the true long-term economic, social and environmental cost and benefits of infrastructure. A key consideration for capturing value is the purpose of the infrastructure service; is it to maximise revenue, or to provide an affordable service or amenity to citizens and businesses?