Existing case studies of control of political corruption often lack a theoretical framework that can provide for systematic empirical research and comparisons between cases and countries. To remedy this, we apply principal-agent theory qualitatively to study the United Kingdom, with a particular emphasis given to an in-depth study of control measures employed to Parliament, the Executive and political parties. We give a detailed account of the approach undertaken to control political corruption in these risk areas for corruption, and discuss its implications and why some types of measures prevail over others.