Professor Neil Ferguson, a mathematician and epidemiologist whose work aided the decision to put the UK in lockdown, has been modelling disease outbreaks for more than two decades.
Prof Ferguson resigned from the Scientific Advisory Group for Emergencies (Sage) on Tuesday after admitting an "error of judgment" by allowing a woman to repeatedly visit him at home during the lockdown.
The scientist is credited with the modelling research that underpins the Government's coronavirus strategy.
He heads Imperial College London's Covid-19 response team, which modelled the spread and impact of coronavirus in a Government-commissioned report. It was this modelling which indicated efforts to merely slow the spread of the virus may have led to 250,000 deaths if that strategy were followed.
In the wake of the report, the PM announced the lockdown on March 23 - ordering the public to stay at home.
As director of the MRC Centre for Global Infectious Disease Analysis at Imperial, Prof Ferguson's research is used to advise internationally through collaboration with the World Health Organisation. Prof Ferguson has used mathematical modelling to provide data on disease outbreaks over the last two-and-a-half decades. With a specialism in the study of infectious diseases which spread in humans and animals, Prof Ferguson's research began with bovine spongiform encephalopathy, commonly known as mad cow disease, in the 1990s. He later researched variant Creutzfeldt-Jakob disease, a rare related illness in humans first identified in 1996.
Prof Ferguson carried out modelling on the foot-and-mouth disease outbreak in 2001, warning that earlier culling could have reduced the four million animals killed by up to 30%.
He was awarded an OBE for services to epidemiology and the control of infectious diseases in 2001. Prof Ferguson was later tasked with assisting Defra during the 2006 bird flu outbreak, modelling the spread to assist with future management.