Gyratory traffic schemes, extended one - way systems etc

If the few I have to deal with are representative, they tend to be very wide (4+ lanes) which causes drivers to act like they're on a motorway and drive aggresively with no consideration for slower more vulnerable road users. Hard acceleration, unindicated lane changes, rushing red lights and so on. The scale is out of step with the environment (urban).

Exactly right. In a way, of course, people are on a motorway there--or at least on what was built of the motorway. It's unbelievable today, but the plan last century was to start with constructing massive junctions (as that's where 'traffic' gets its knickers in a twist the most) and then widen lots of streets by knocking down tens of thousands of houses. More than fifty houses were apparently demolished to build the Lea Bridge roundabout, not to mention Brooke House, Hackney's saddest post-war loss:

http://en.wikipedia.org/wiki/Upper_Clapton#Brooke_House
http://ezitis.myzen.co.uk/brookehouse.html