not AS they turn because they are about to knock you over as you are in the middle of crossing the road.
They know in advance they will turn left at the light, why leave it till the last minute. This morning driver almost knocked over this woman with her child on the school run and had the nerve to swear at them, when I clearly saw the mom look out for cars turning in and the driver did not indicate as he approached.
I see a lot of this in London. Some don't bother to indicate at all. I guess now I have kids I notice it even more.