I've found the drivers in London to be better in general than the rest of the country. There are cyclists EVERYWHERE. No car is surprised to share the road with one and they all know what to expect from them. I'm not saying everyone gets along, but I've never felt particularly unsafe, and I used to ride 27 miles total commute a day.
Contrast that with other cities I've lived in where cyclists are more of a rarity. The motorists simply don't expect them, so they don't factor them in to decisions like how much stopping distance they'll need, whether they'll bother to look left before turning, whether there could be something behind that bend (when you can see 1/3rd of the road and so expect to see something as wide as a car). They also expect to average a much higher speed, and so IME get aggressive much more quickly when they feel they're being held up.
Don't even get me started on countryside drivers, with their 70mph round blind bends on two way roads not wide enough for two cars...