I never understood the prisoner . I was very young but there seemed to be a lot of yelling back and forth and always hearing that voice yelling number nine , what seemed like all the time , turned me off from watching the show . Good actors tho .
from what i remember from it --watched it on YT about 3 yrs ago-- the main character was a James Bond type.
He was in a position of high trust and security clearance for british intelligence
one day he quit and left..no debriefing, etc
given the current climate of the time (anti war, anti govt, anti establishment) I think that the nature of the show and how the character was treated and imprisoned was the way the creators expressed how they thought a man such as this would be treated in a situation where he basically went AWOL. that is how those in the counter culture perceived such a scenario
a good show about the needs and rights of an individual resisting the lure, safety and order of the collective