Geograph - photograph every grid square

The North London line (NLL) is a railway line which passes through the inner suburbs of west, north-west and north London, between Richmond in the south-west and Stratford in the east, avoiding central London. Its route is a rough semicircle. The line fully opened in 1869.
Wikipedia. Link

A few years ago I read a book by Mark Mason "Walking the lines" in which he walked the route of the London Underground lines, overground. I will repeat this visiting all 272 stations (some more than once). My route tries to follow the line of the railway as closely as possible, using footpaths and roads, deviations are made to make the walk more "interesting".