Geoffrey Grimmett is an internationally renowned mathematician with a broad interest in probability and disordered systems. Randomness is ubiquitous in the theory and applications of mathematical science, and much of Geoffrey's work is concentrated on understanding the properties of large systems of randomly interacting objects.

His major contributions include his work on self-avoiding walks, percolation theory, and the random-cluster model — an important mathematical tool for studying ferromagnetism. He has written a number of oft-cited books on spatial disorder and other aspects of his research, and he has co-authored several textbooks on probability and random processes.

His current focus on the theory of disordered physical systems is motivated by practical problems that arise in the applied sciences such as physics and biology. These include models of a disordered medium and the spread of epidemics. In 2013, Geoffrey became the master of Downing College at the University of Cambridge.