I was driving to a regular leisure activity this morning, when I noticed in my rear view mirror that the driver of car behind appeared to be on his mobile phone (with his hand up to his ear). He followed me for about 2 miles during which time we negotiated roundabouts as well as left and right turns. Each time I checked my mirror, he was still on the phone.
By coincidence, he pulled up at exactly the same place as I did and was still on his phone when I walked past his car and into the building. I was still by the door when he walked in (having now finished his conversation) so I turned to him and said "Can I recommend that you invest in a hands free kit for your car". He looked at me as if he didn't know what I was talking about whereupon I explained that he had been driving behind me for some distance and I had noticed that he was illegally using his phone. His response was to ask me if I was a police officer and I questioned what difference that made, as clearly even if I was then I was off duty. I told him I was merely pointing out, as another road user, that he was unnecessarily breaking the law and could easily rectify it in future. He clearly took exception to me and was not about to admit to the error of his ways as he asked me "if I'd had a bad night?" I replied that I hadn't but that I just took exception to other road users who put other peoples'lives at risk.
At that point we went our separate ways and got on with what we had come for.
So WIBU to have challenged him in the 1st place in the hope that he will change his ways. I will add that I was old enough to be his mother and I have my own teenage son who has just passed his driving test and am constantly telling him "it's not just about how you drive, it's the other idiots on the road you have to watch out for".