Long before it became fashionable to question the economics of the nuclear industry, Sweet went against the prevailing assumptions of the then Central Electricity Generating Board, that nuclear energy would be either safe or cheap. As such, he became the leader of an expanding group of environmental activists and academics and took a leading role in opposing the development of what has since become the Thorp reprocessing plant, at the 1977 Windscale Inquiry.
Sweet's opposition to the nuclear industry was deeply felt and reinforced by his antagonism to nuclear armaments. Educated at the London School of Economics, he joined the Communist Party at the end of the Second World War. Evacuation to a Welsh mining village in that war had taught him a fierce socialism and the Communist Party gave him access to some of the brightest left-wing minds of his day.
Amongst men like Bertrand Russell, J.D. Bernal, John Berger and Eric Hobsbawm, the young Sweet found himself a vocation with the British Peace Committee. Acting for 12 difficult years as its Secretary, Sweet had the distinction of inviting Picasso to a congress of the committee, only to be forced by the British authorities to cancel the event after Picasso had arrived.
Needless to say, if the British authorities found the younger Sweet tricky to handle, so did the Communist Party, whose line he consistently flouted. He left it in the early 1970s to lecture at the then South Bank Polytechnic. Here, he founded the highly valued Centre for Energy Studies and began his long-term crusade against nuclear power and the dangers of nuclear proliferation.
As well as leading the denunciation of nuclear reprocessing, he became one of the leading British advocates of renewable energy. He was asked in the early 1980s by the European Parliament's Science and Technology Options Assessment unit (STOA) to examine the future of Europe's nuclear fusion programme. His report, put together with a number of scientific advisers, was the first important independent analysis of the billions of ecu going to fusion research and it was damning.
Put at its simplest, Sweet's conclusion was that a research effort culminating with something useful only in 2060, if then, was hardly amenable to any kind of serious economic evaluation and had huge opportunity costs. The time-scale and money involved was in itself a huge revelation and created a widespread feeling in electricity circles that fusion - for all its promise - would never be economic. Ironically, his view that the fusion programme was a monstrous waste of EU money brought him the private plaudits of his former enemies in the nuclear fission industry; a fact which amused him.
Sweet was an unashamed polemicist. He made no secret of his detestation of laissez-faire capitalism and neoclassical economics and he attacked them with a style and verve that gained him the respect of his opponents.
If he sometimes seemed to be out of tune with the fashions of his time, fashion had a habit of catching up with him. In mid-1990s Britain, few people now put bets on more nuclear power stations, nuclear reprocessing is widely regarded as unnecessary and renewable energy is seen as vital for the future. Some are even questioning the value of neoclassicism. Colin Sweet would be pleased about that.
Colin Sweet, political activist: born 11 June 1927; married (two sons, one daughter); died 5 June 1995.