I am an epidemiologist with a statistical background. My research is driven by a desire to improve the health of young children and their mothers in low and middle-income countries, and to increase access to known effective interventions. It is focussed on informing priority policy issues through tackling gaps in evidence to enable effective decision making for maternal, newborn and child health and nutrition policies and programmes. I have made major contributions in the following areas: (i) Cluster randomised controlled trials evaluating the delivery through community-based workers of key known effective interventions for (a) newborn and child survival, and (b) early child development and growth; (ii) Definitive trials evaluating vitamin A supplementation strategies; (iii) Evaluating key maternal, newborn and child health interventions (including breastfeeding, access to facility births, water supply and sanitation) (iv) Increasing access to treatments for common mental disorders; (v) Understanding the epidemiology of childhood diarrhoea and pneumonia.

My substantive research has been accompanied by a commitment to translating research findings into health policy and programme action, to teaching, to research capacity strengthening, and to making complex epidemiological and statistical methods accessible to public health researchers and policy makers. The latter led to my textbook "Essential Medical Statistics", first published in 1988.

I have an extensive network of overseas collaborators and close links with the World Health Organization, including serving on the Strategic & Technical Group of Experts (STAGE) for maternal, newborn, child & adolescent health and nutrition.

I am a fellow of the Academy of Medial Sciences and a fellow (by distintion) of the UK Faculty of Public Health. In 2017, I received the George Macdonald medal in recognition of outstanding research leading to improvement of health in the tropics.