Highway Code says horns should be used as a "I'm here' warning. Perfectly reasonable to alert the driver to the fact they were about to wang into you. Doing them a favour even. We will all need dash cams soon to provide evidence if things get nasty. Stay safe. (Oh how I hate that expression at the moment!)
What were the first ever records that you bought and when?
Army horses loose on London streets
Can I use my bus pass on London buses?