The French would not have been alone in their bafflement. Even in Britain Joseph Rotblat was hardly well known before Friday, and the name Pugwash was only likely to raise a laugh. Yet Professor Rotblat has been campaigning for nuclear disarmament for half a century, and the Pugwash movement has been going almost 40 years.
What sort of pressure group remains so discreet for so long? What sort of pressure group calls itself Pugwash? Above all, what sort of campaigner remains unknown for decades and then wins the Nobel Prize?
Joseph Rotblat is the quintessential activist. Even at 86, his eyes gleam with a missionary light, he is hyperactive to the point of jumpiness, and he has little time for any argument that is not directly to the point. Although he had a long and successful academic career, he seems to have only one thing on his mind: nuclear disarmament.
His charm is undoubted and his manners courtly; when he speaks, his light voice still bears the accent of Poland, and he is still handsome, appearing even with his white hair to be at least 20 years younger than he is. But all the time, behind those eyes, that sharp mind is bent on its objective.
It is his extraordinary motivation and clarity of vision that keep him going even now, when the Cold War is over, towards a goal once dismissed as ludicrous but now entering the realm of possibility: a world completely free of nuclear weapons. Of all the British scientists who set out on this path in 1945 and 1946, he is almost the only one still walking it.
Flick back through the pages of his life to the winter of 1947-48 and you will find him aboard the "Atom Train" at a railway platform in some British city. The train, which Rotblat did more than anybody else to make a reality in the teeth of opposition from as high as the Cabinet, was a rolling exhibition of the nuclear world, intended to raise public awareness of the issues of the new age.
Visitors were told - sometimes by Rotblat himself - of the peaceful uses of the atom, in electricity generation and in medicine, and of its military uses as demonstrated at Hiroshima. The final exhibit ended with the question: "Which will it be?"
Flick forward to the1950s and Rotblat, giving a televised lecture on radiation, is illustrating a point by drinking a beaker of mildly radioactive liquid - an "atom cocktail", as the press put it. As a Geiger counter follows its progress downwards, he explains that his purpose is to remind the audience that radioactivity need not always be a cause of terror.
Forward again to 1980 and the aftermath of the Soviet invasion of Afghanistan, when relations between East and West are as cold as they ever were. Rotblat has organised a Pugwash Conference (the name is taken from the site of the first meeting, in Nova Scotia in 1957) at which scientists from the West and the Soviet Union talk even while their governments refuse to.
This has been his life's work: bridging the gap between scientific advance and public or political understanding. For him the pivotal moment came in 1945, when for eight months he worked as part of the British team at the US atomic bomb laboratory in Los Alamos. He was not the first scientist to see the implications of the Bomb - the Dane, Niels Bohr, among others, was ahead of him - but of those at Los Alamos he was the first to act on it.
As soon as Germany was defeated he demanded to leave, declaring that since the Allies no longer faced the threat that an enemy might develop atomic weapons (Japan did not have the capability), there was no moral justification for continuing the work. Amid some acrimony he was allowed to go.
A few months later the Bomb was dropped. Among the many things it changed was the relationship between science and the state. Here was a weapon conceived and developed by scientists which in a short time had transformed the political balance of the world. Should it have been invented? Should it have been dropped? What should happen next? It seemed that apart from soldiers and politicians, scientists were the only people who had answers.
In this atmosphere, Rotblat and others established the Atomic Scientists' Association, aiming both to inform the British public about the peaceful potential - as it was then perceived - of nuclear energy and of the true risks of atomic weapons. In the hope of preventing an arms race, they supported the idea that the nuclear industry worldwide should be placed under United Nations control.
The Cold War came and the ASA failed. Rotblat determined on a new approach, and this became Pugwash.Where the ASA had been the Atom Train, pamphlets, public meetings and popular science, Pugwash was low-key and high-level. The typical Pugwash meeting takes place in a place that is not a capital city, is closed to the press and issues a statement afterwards that is both bland and worthy. Yet its confidential reports will afterwards be circulated to presidents and prime ministers.
The conferences could not have continued through the worst of the Cold War had they not been quiet affairs. They were sometimes criticised in the West for providing Moscow with a platform for its views, yet they kept open the lines of communication on disarmament and identified possible ways forward when no other forums existed to do so. The basis for several disarmament treaties, including the Anti-Ballistic Missile Treaty and the Non-Proliferation Treaty, is often said to have been laid at these obscure meetings.
And the work goes on. A few weeks ago, the British branch of Pugwash produced a report that summed up the organisation's style. It was written by three men: Rotblat, himself an authority on radiation biology; the late Professor Sir Rudolf Peierls, a leading physicist and Los Alamos veteran; and Sebastian Pease, former chief of the Culham fusion laboratory - men of impeccable scientific credentials whose views no one could lightly dismiss. It was dispassionate, rational and never moral in its approach. It asked "Does Britain need nuclear weapons?" and it answered, very convincingly, "No".