This report examines the science advisory system in the UK, how it has changed and how it may develop further in the future. It looks at structure and functions within the UK Government (including the Government Chief Scientific Advisor, the Government Office for Science, government departments, scientific advisory committees - including SAGE - and the Science and Engineering Profession). It also describes science advice in the UK Parliament. The report looks at the role of public research funders, particularly UK Research and Innovation and its research councils, and it discusses how universities are responding to incentives to improve the supply of evidence and expertise. There are brief sections discussing the role of other actors (such as national academies, charities and industry) and discussion of some cross-cutting themes.