The following is an excerpt from "A history of the Campaign for Nuclear Disarmament (CND) (CND) logo" by the CND in UK.
One of the most widely known symbols in the world, in Britain it is recognised as standing for nuclear disarmament - and in particular as the logo of the Campaign for Nuclear Disarmament (CND). In the United States and much of the rest of the world it is known more broadly as the peace symbol.
It was designed in 1958 by Gerald Holtom, a professional designer and artist and a graduate of the Royal College of Arts. He showed his preliminary sketches to a small group of people in the Peace News office in North London and to the Direct Action Committee Against Nuclear War, one of several smaller organisations that came together to set up CND. The Direct Action Committee had already planned what was to be the first major anti-nuclear march, from London to Aldermaston, where British nuclear weapons were and still are manufactured. It was on that march, over the 1958 Easter weekend that the symbol first appeared in public.
What does it mean? Gerald Holtom, a conscientious objector who had worked on a farm in Norfolk during the Second World War, explained that the symbol incorporated the semaphore letters N(uclear) and D(isarmament).