 This required him to take U.S. citizenship, but due to the risk of Vietnam War conscription he returned to the UK.From the mid-1960s until 1986 Large was an academic in Brunel University's School of Engineering, becoming a lecturer in 1971, where he undertook research for the United Kingdom Atomic Energy Authority.During the 1980s, Large was an advisor on nuclear issues to Shadow Secretary of State for Energy Tony Blair.