By Kathryn Westcott BBC News

It had its first public outing 50 years ago on a chilly Good Friday as thousands of British anti-nuclear campaigners set off from London's Trafalgar Square on a 50-mile march to the weapons factory at Aldermaston.

The demonstration had been organised by the Direct Action Committee Against Nuclear War (DAC) and the Campaign for Nuclear Disarmament (CND) joined in.

I drew myself: the representative of an individual in despair, with hands palm outstretched outwards and downwards in the manner of Goya's peasant before the firing squad Gerald Holtom

Gerald Holtom, a designer and former World War II conscientious objector from West London, persuaded DAC that their aims would have greater impact if they were conveyed in a visual image. The "Ban the Bomb" symbol was born.

He considered using a Christian cross motif but, instead, settled on using letters from the semaphore - or flag-signalling - alphabet, super-imposing N (uclear) on D (isarmament) and placing them within a circle symbolising Earth.

The sign was quickly adopted by CND.