Quite a lot.Which graphically illustrates why "Having a word" is pointless. If even cyclists accept the inattention and lack of consideration of motorists as part and parcel of using roads in the uk, what chance have you of changing anyone's mind?
I had occasion once to have a "word" with a chap in a blue van who cut me up badly (he was on his mobile at the time). I caught him up at the next lights, and had a quiet, calm chat with him.
I encountered him several times in the following weeks. Each time he overtook me with care and consideration, followed by a "toot toot" and a wave.
It can't get better than that?