John Large is a Chartered Engineer, a Consulting Engineer, a Fellow of the Institution of Mechanical Engineers,  Graduate Member of the Institution of Civil Engineers, Member of the British Nuclear Engineering Society-Institution of Nuclear Engineers, and Fellow of the Royal Society of Arts.

From the mid-1960s through to the late 1980s, John Large was a full-time member of the Academic Staff at Brunel University and, transferring his academic interests, he founded Large & Associates in 1986 specialising in the nuclear field.

John Large has prepared and given evidence to the Court of Human Rights at Strasbourg,  to a number of House of Commons Select Committees, quite frequently he provides expert evidence on aspects of system failure and technical issues in the UK Crown and Civil courts.  He has given evidence to overseas governments and agencies, including the governments of New Zealand, the Russian Federation, Finland, Bulgaria and to the US Nuclear Regulatory Commission on the risk of nuclear terrorism.   John Large was awarded a commemorative medal for his contribution to the Kursk salvage by the Russian authorities. 

John Large is a nationally and internationally recognised professional, consulting  engineer who, not infrequently, contributes comment and opinion on nuclear and technical matters to national and international media.