Great post, Paul.
I've worked in the City of London since 1999 and I visited London regularly even when I was working back "up North". Good to see that the Underwground (smoking and dubious hair and clothing styles aside) remains the grimy hole in the ground it has ever been.
I have what I call my 3-stop "rule". Essentially, unless the destination requires me to travel more than 3 stops, I walk as the Underground trains are usually packed, swelteringly hot and it is vastly over-priced.