Stephen is Medical Research Council Clinical Professor of Immunopharmacology at the University of Southampton with a research interest in the mechanisms of asthma and allergy, with over 1000 peer reviewed publications. His research has focused on the roles of air pollutants, allergens, and viruses in driving airway inflammation, and remodelling involving injury to the epithelium and aberrant repair. In 2003 he cofounded a University of Southampton spin out company, Synairgen, to develop inhaled interferon-beta for the treatment of viral exacerbations of asthma and COPD. He was the founder chair of the Committee on the Medical Effects of Air Pollutants, chair of the Expert Panel on Air quality Standards, the Hazardous Substances Advisory Committee, and was a member of the Royal Commission on Environmental Pollution. He is Special Advisor to the RCP on Air Quality and in 2016 and 2020 published two influential RCP and RCPCH reports on the health impacts on air pollution.

He has been President of the British Society for Allergy and Clinical Immunology, British Thoracic Society, British Association for Lung Research and the Collegium Internationale Allergologicum. He has been Chair of MRC Population and Systems Medicine Board, the MRC Translational Research Group, Member of MRC and NERC Strategy Boards, Chaired the Main Panel A (Health and Life Sciences) of the UK Research Excellence Framework 2014, and is Deputy Convenor of the Hong Kong RAE 2020.

His contributions have been recognised by a number of awards including The King Faisal International Prize in Medicine, the J Allyn Taylor International Prize in Medicine, The British Thoracic Society Medal, Distinguished International Fellow of the American College of Allergy Asthma and Immunology, Lifetime Achievement Award of the World Allery Organisation, and is the 2020 recipient of the RCP Faculty of Public Health Bazalgette Champion of Evidence Award. He has Honorary Degrees from the University of Ferrara Italy, Krakow Poland, Naples Frederico II, Italy and Exeter, UK. He was a Founder Member of the Academy of Medical Sciences, served on its Council and is Founder Chair of the Clinical and Veterinary Section of the Academia Europaea. In 2011, he was appointed Commander of the Order of the British Empire in the Queen’s New Year Honours for Services to Clinical Science.