After my experience yesterday evening, I nominate the Victoria line platform at King's Cross / St Pancras to Platform 1 at St Pancras. Anyone know of any longer walks between trains supposedly at the same interchange?
I'm sure I recently read somewhere that at Kings X / St Pancras and some others
TFL▸ deliberately route you along long corridors so as to avoid congestion on the direct quicker route. The story I read was that it was actually quicker to follow the Way Out signs and then change at street level.