Someone made a comment about "we're worried about the price of gas." I think it's human nature to focus on something that affects one directly rather than something more remote. At the end of the day, it's overwhelming to contemplate all the troubles in the Middle East, Korea, terrorism, etc. So a person gets fixated on how long the line is, how expensive gas is, etc.

As far as the "source" of the plot goes, I think it may be combination of MI5 and Scotland Yard surveillance, and use of informants. Use of informants ("snitches" ) is a time tested part of police work. If the cops want to keep the informant in place, they keep to themselves who it is!