Be aware of the traffic lights and the crossing traffic in London... my cousin explained it to me like this: 'Green means watch out, yellow means speed up and red means 4 more cars to go thru...' heh heh heh... no more comments...
Do not leave anything valuable in your car. We had a rental car outside a restaurant at lunch time and someone smashed a window to get at what he thought was a laptop computer. He dropped it and ran when we came out but we had to get another rental car and were delayed for a couple of hours.
This is supposedly not an uncommon event. Park your car where you can see it if you can and definitely don't leave anything that even looks valuable inside that can be seen from outside.
Just like to remind you that like other places, London doesn't like trash lying around. Please use the litterbins... they have places for recycling and for garbage. This was taken in Victoria Park.