It's hard to comment on a dynamic situation when we've only a snapshot to see. But I agree with you about the problem of vehicles piling up behind – it may be legal to continue to cycle for miles, holding up a queue of cars, but it's not considerate. If cycling, I'll usually find a way to let faster vehicles get past me if they've been following for a while.

While I welcome the imminent changes to the Highway Code, I can see the potential for more frustrated drivers. And it's exacerbated by the fact that UK drivers aren't taught to overtake (unless they've taken advanced training, which is rare). Consequently, people learn to overtake by making it up as they go along!