The besmirched tiles were seemingly uncleaned since Turnham Green station opened in 1869. That overheard remark sparked an idea. Now, one of London's filthiest walls is covered in cartography.

Chiswick Park Station. It's actually closer to Turnham Green than Turnham Green Station is, and is located close to the site of the 1643 Battle of Turnham Green. Photo: Andrew Lachlan Chiswick.