HAS TO BE!!!
I really want to know how you got both the mottled effect of very similar but differing tons on each tile and the glased look... the colours are spot on for that bit of line!
The tiles were pre-painted white and brown and then washed with a warm grey and rubbed clean several times. Now they gloss a bit due to the rubbing/polishing effect and look dirty by the wash at the same time...

Sorry, no Mornington Crescent for me, as it is located along the Northern Line and no Hobbs End, because that would be on the Central Line:

'I wonder if Michi's doing escalators...?'
Michi is not going to make escalators. There will only be stairs, but these will be nice as well!