I can't recall what the graffiti is like on that stretch, but in general Network Rail's control of graffiti is appallingly lax. In contrast, London Underground insisted some years ago that their PPP partners, Metronet and Tube Lines, must tackle the problem with determination, and this was done. It meant that a lot of bare brick was covered in a sort of brown colour, but once that had been done, any new graffiti was very rapidly painted over. And that standard has been maintained. Network Rail shoukld do likewise.
Richard Jennings ● 5817d