Were there lyrics to the theme song? The lyrics on that song in a search are bad but may not be associated with that.
The Prisoner: “Who are you?”
Number 2: “To you - Number 2.”
The Prisoner: “Who is Number 1?”
Number 2: “You are number 6.”
The Prisoner: “I am not a Number! I am a free man!”
Number 2: (laughter)
The show itself had a purely instrumental theme song. Years later Iron Maiden (best read heavy metal band ever) did not one but two Prisoner inspired songs. The first was “Prisoner” on their Number of the Beast album, that’s the one that starts with the “who is #1” exchange, good song written by the band’s main guy Steve Harris. The second was “Back in the Village” on their Powerslave album, that song is mostly constructed of memorable lines from the series like “questions are burden, answers a prison for oneself”, it’s a little clunky and not one of Bruce Dickenson’s best efforts as a writer.