 In 1986, he founded the London-based consulting engineers Large & Associates, which specialised in analysis of and reporting on failure of engineering systems, particularly in the nuclear field, which at one time employed up to 40 people.The International Atomic Energy Agency (IAEA) invited Large to visit China, Korea and Iran to give advice on their nuclear programmes.He visited Japan on behalf of Greenpeace following the Fukushima Daiichi nuclear disaster, and his first technical assessment confirmed a triple reactor meltdown well before it was officially acknowledged.