Help with a quote

I remember this series mostly for a great quote said by the lead character to his girlfriend at the time but I can't remember how it went exactly.
It was something like "when you get between the public and what they want you will always fail" and he was talking about drugs at the time.
Can anyone give me the exact line? and who he is quoting?
I think in the same episode he said the old saying the "if you want to know the time ask a policeman" came about because in Victorian times the "beat" coppers used to steal drunk gentlemen's watches so they always had a watch where most people did not. If that's any help.