griff, I live in France where cyclists and motorists cohabite with a certain harmony. It is cultural like in Belgium and Holland where cycling, as a sport, is huge and where the population use their bikes in built up areas as their main means of transport.
I left London many years ago and never went back for years. When I did return it was after London had introduced the congestion toll. I was astonished about the number of cyclists that I saw on inner London roads, it was almost worthy of Amsterdam..At the same time I noticed a certain anarchy concerning some of the cyclists, therefore I can imagine your frustration when you are confronted with them.
On a personal note I very rarely use my bikes as a means of transport but are used 99% of the time for my sporting activities on minor country roads in the area where I live and frankly have rarely had any problems with irate motorists.
Vive le vélo!