... and I have never understood how the 'average speed camera' can actually work.
I have encountered them many times, and I try to stick to the limit, despite always seeing drivers flying past me at a higher speed. They don't seem to care, so can they actually work?
For example, I pass a camera doing 55mph, (the limit being 50mph say) and I change lanes regularly... then how can the next camera accurately recognise my vehicle?