Fifty years ago on a cold, grim Easter holiday, a protest was meant to be a watershed: a global call to ban the bomb.
People marched from London to a factory in the countryside where Britain built its atomic bombs. Pat Arrowsmith was among those early campaigners for nuclear disarmament.
"It was quite clear that we were not just against the tests, and we were not just against the British bomb," Arrowsmith said. "We were against the Soviet bomb and against the U.S. bomb."
The nuclear weapons industry at Aldermaston is still very much alive. But so is the spirit of that protest fifty years ago. It lives on in a symbol born here that became an icon.
Gerald Holtom was the artist and textile designer who created it.
A conscientious objector during World War II, he was driven to the nuclear disarmament campaign, he said, by a feeling of despair.
Holtom's daughter Anna Scott, also an artist, remembers the image of her father's despair, in the paintings of Goya.
"He used the Goya painting of the despairing image of the person who was being shot, in Spain - I don't know whether the despair was to do with his personal situation or whether it was to do with the world situation, and sometimes these can be muddled up, can't they?"
Working in his West London studio, Holtom sought to transform that muddled despair into something tidy and neat: a symbol for the campaign for nuclear disarmament, based on the Naval sign language of semaphore.
Michael Randle was there in 1958 when Holtom explained his idea: matching the 'N' for nuclear & a straight up-and-down 'D' for 'Disarmament,' with a circle around it. "That's the symbol, very simple and straightforward," Randle recalled. "It was that explanation coupled with his vision of what the march would be like, his sketch of what the march would be like, that really sold it to us and we said, 'Right, we will adopt that.'"
Not without controversy. It was inevitable that Holtom's simple three lines and a circle would bewilder at least one of the anti-nuclear campaigners.
"He looked at it and he said, 'What on earth were you three thinking about when you adopted that symbol? It doesn't mean a thing and it will never catch on.' Of course, he was thinking of the traditional things of a broken rifle, or a dove or something that would be immediately associated in people's minds with peace, and if you're looking at it now it's impossible to separate it from all the history that has gone on since."
Impossible, almost, to imagine some history without it.
The 'n' and 'd' of nuclear disarmament were its source, but its meaning quickly embraced a bigger cause: as a symbol for protest in the broadest sense, more specifically as a sign for peace.
An international brand that became as familiar as a stop sign - from grim and gritty, to groovy, like a universal trademark, according to design consultant Richard Williams.
"The clever thing about it is, it's a mark we can all remember," Williams said. "Because we can all draw it. You have to see it once to be able to draw it and there are very few marks that work that way. That's why it can grow so quickly, why so many people can adopt it, because they can just scribble it. So when people were making placards they didn't get it wrong, they knew what it was."
And because Gerald Holtom and the anti-nuclear campaign deliberately didn't copyright the symbol, no one owns it - or, perhaps everyone does.
"We believe that brands don't belong to companies, they belong to people, they're made in people's minds," Williams said. "This isn't a brand, this is much more than that. This is a movement and an attitude of mind.
"It's the dream of every brand owner to get in there and own the territory, and [this] happened to do it and did it very well."
CND, the Campaign for Nuclear Disarmament, is still doing it: printing signs, preparing for another march. It never managed to ban the bomb. But the spirit of its symbol is still booming.
"It's been used as a badge against tyranny in Greece," recalled Arrowsmith. "It's been used as a badge against apartheid in South Africa, it's been used just as a general peace logo, it's been worn by U.S. U.S. troops opposing the war in Vietnam, it's become very much an anti-war symbol, but also an anti-tyranny symbol.
"I think it's a good symbol because it is actually quite simple"
Simple, as simple as the three lines and a circle, etched on the headstone of Gerald Holtom's grave.