The document outlines a review of the UK government's Infrastructure and Projects Authority (IPA) assurance model. It finds that while IPA reviews can be high-quality, valuable, and focused on key issues, they are not always consistent in quality. The review recommends changes to ensure assurance is applied appropriately and quality is managed. It suggests the IPA transform to take a stronger portfolio view, focus on highest risks, get involved earlier, and ensure access to experienced experts, to have greater impact in supporting the government's major projects.