He was elected Fellow of the Academy of Medical Sciences in 2000, Foreign Member of the Brazilian Academy of Sciences in 2007, Fellow of the Royal Society in 2012 and Honorary Fellow of the British Pharmacological Society in 2015.
Professor Williams has supervised 28 PhD students and examined 71 during his career. His research is focused on inflammatory mechanisms with an emphasis on those underlying the recruitment of different leukocyte types to sites of inflammation. Many of his papers are concerned with the role of chemokines in eosinophil recruitment. More recently he has become interested in mechanisms underlying the population of tissues by mast cells and the chemotactic receptors expressed by mast cell progenitors.