I am a Professor of Computer Science at University College London and a Research scientist at Facebook. My research has stretched from abstract topics such as category-theoretic models and logics through to logics of programs and on to automated analysis of industrial software in the million of lines of code and its deployment to products used regularly by billions of people. I like to think that fundamental theory, tool development and application can and even should play off one another via mutual feedback in computer science research, in a way reminiscent of the experimental method.