I feel lucky to be sitting here typing this.
I had just left the Stanmer Woods car park this afternoon and was heading up the hill when a police car overtook another car on the blind brow of the hill and was heading straight at me. Fortunately there had been no time for me to build up any sort of speed and I was able to stop instantly. Had I been coming from the foot of the hill I would have been travelling faster and would probably have been unable to avoid a head-on collision. Yes, he had flashing lights and two-tones on, but I couldn't see the lights until he crested the hill, and the sound of the horns was deflected by the hill so I couldn't hear those.
It might have been nasty, but thank heavens it wasn't.