My research has always been influenced by my own farming background, and so has focussed strongly on interactions between farming and the environment. After a few years teaching biology at what is now Anglia Ruskin University, I joined the Centre for Ecology and Hydrology in 1991, looking at large-scale interactions between agriculture and biodiversity. I led the UK Farm Scale Evaluations of GM crops, the largest agro-ecological experiment undertaken at the time; I am still highly involved with the risk assessment of genetically modified organisms (GMOs) through my membership of the EFSA GMO panel.

I also studied the ecological consequences of organic farming and agri-environmental schemes. I moved to become Head of North Wyke Research in Devon, which focuses on environmental aspects of cattle and sheep farming, and has now merged with Rothamsted Research. I led the design of the North Wyke Farm Platform, a farm-size experimental facility to test the sustainability of different approaches to livestock farming. I have led the work on standardising ecological variables within the European ExpeER programme.