Sir Mark Walport leaves Wellcome Trust after a decade in charge
13 March 2013 Last updated at 17:45 GMT
Sir Mark Walport has been Director of the Wellcome Trust for 10 years and at the end of March is leaving to take up the post as the government's Chief Scientific Advisor.
Wellcome provides more than £600m in research grants each year, making it the second biggest charitable health body in the world after the Gates Foundation.
The BBC's medical correspondent Fergus Walsh asked him for some of the major highlights in the world of science in the past 10 years.