Following his PhD, George was awarded a Beit Memorial Fellowship to carry out postdoctoral research at the Tenovus Laboratories. He then went to the National Institutes of Health to work in the laboratory of Dr David Segal, developing recombinant antibody-based molecules. He returned to the UK in 1992 to a lectureship at the Royal Postgraduate Medical School, Hammersmith Hospital (which merged with Imperial College London in 1997).