Away from the dirt, Jag from Route79 uncovered something about the walkway that connects the Jubilee Line and Piccadilly Lines at Green Park
He said "walking at a brisk pace is what I normally do whenever I have to do this tunnel. So brisk that I never really notice a very clever but quirky little detail about this walkway.
"We all know that the colour coding used on the Tube is excellent, consistent and familiar. For example, that the colour of the Piccadilly Line is dark blue and and the Jubilee Line is grey (or silver), but did you know that as you walk from the Picc platform to the Jub platform through this tunnel at Green Park, the tiny little mosaic tiles on the white walls of this tunnel start off with speckles of dark blue only and then gradually become a mixture of dark blue and grey as you progress through the tunnel, eventually becoming grey only at the Jub Line end?"
I like to think that I know my Tube mosaics, but London Underground still manage to surprise me with their designs. Like Jag I've done that walk loads of times and have never noticed that before. Do you have a favourite little known design "secret" about the Tube?