Patrick McGoohan was already a huge international star thanks to his role as spy John Drake in Danger Man when he dreamt up The Prisoner.
After six years McGoohan had tired of playing Drake. ATV chief Lew Grade, worried that he would lose one of his biggest assets, accepted McGoohan's pitch for a new series.
Thanks to Lew Grade's 'hands-off' approach, McGoohan and script editor George Markstein were able to give full reign to their creativity - and an enigmatic, non-violent gentleman-hero was born.
Resigning from his post, Number 6 (we never find out his name) is drugged and incarcerated in The Village, a strange un-wordly place presided over by various Number 2's.
Each week Number 6 would try to prove that he wasn't a number, but a free man and attempt to escape - and each week he would be thwarted by Nuumber 2 and 'Rover', a huge white balloon guard.
But where was the Village, who was Number 6, or indeed Number 2? The series kept on throwing up questions, but steadfastly refused to give viewers any answers.
With its fresh visuals, great theme tune, inherent eccentricity and McGoohan's refusal to comply with the conventions of TV drama, the show was an instant hit and regularly attracted around 11 million viewers.
The show was such a success that Lew Grade persuaded McGoohan to make more episodes so that he could sell the series overseas - originally McGoohan thought that seven episodes would do the idea justice.
Markstein left the project after episode 11 over 'creative diferences', leaving McGoohan to realise his vision - the result was an unconventional ending that has puzzled audiences and fans to this day.