Legal Graffiti

I was walking towards Tonbridge Parish Church this morning, when I spotted this incredibly bright and ugly graffiti in Church Street. Why is it there and what is it ... I asked myself?? It could possibly be there as a marker for maintenance reasons which I find extremely annoying. Can't people read maps or follow instructions anymore? Can these people only follow easy to spot enormous symbols? This is part of the conservation area in Tonbridge, and so I'm hoping it's a temporary measure. If not it should be removed as it's a massive yellow blot on the landscape, and nothing more than legal graffiti.