A graphic designer for the British Campaign for Nuclear Disarmament designed it in the late 50's. The design comes from the semaphore positions for the letters N and D.
It was an ironic steal of the famous Second World War "V" for victory sign much used by Prime Minister Churchill. I think Parke described the origin of teh CND symbol, upside own "Y" with an additional vertical enclosed in a circle.
Churchill's salute was a reversal of the traditional English insult to the French. Prior to the battle at Agincourt in 1415 the French nobles threatened to cut of the fingers off the English archers. On the battlefield the English archers held up two fingers to the French to show that they didn't care.
A combination of the words Nuclear Disarment. Also a reaction to the V sign for victory. Peaceloving hippies opposed the fact of victory cuz someone always lost.
Binny is nearly there. Any longbowmen captured by the French during the Hundred Years War had their 1st and 2nd fingers severed (severely AND severally). Archers on the line would hold up those fingers in defiance to show they still had them, rather than not caring.