When is flashing other motorists justified?

James Baggott

Every driver has been there: you're motoring along, then all of a sudden cars on the other side of the road start flashing their lights at you.

After a moment's confusion, you realise what they're flashing about. You slow down, spot the speed camera van at the side of the road and breathe a sigh of relief. Without the warnings you could have strayed slightly over the limit and faced a hefty fine and points on your licence.