Just discovered some information that I think most instructors aren't aware of. Therefore I thought I'd better educate you all!!!!!!!!
Somewhere in the Highway Code, somewhere we're not aware of, it says that you only have to indicate (you know those orangy flashing lights some cars have) when you are joining a main road.
I've noticed that on back streets people who don't indicate, do so when joining a main road. 
So many people act this way we instructors are obviously missing something.