I was fascinated to read about the abandoned tube tunnels which run underneath Borough High Street. They were built as part of the first deep tube line, but abandoned in about 1900 when the route was enlarged (and re-tunnelled) to form the current Northern Line.
Apparently they were used as air raid shelters in the second world war, but most of the entrances were filled in in about 1960. Maps here showing the air raid entrances:
There's a nice write up about it on the Abandoned Stations website including pictures of the tunnels themselves - describing the original route from Stockwell to King William Street.
It's fascinating stuff. One of Nick Catford's books has some lovely pics dating back to about 1980, so before parts of the southern side of the tunnel were obliterated by the Jubilee Line Extension. I hadn't seen the diagrams you've included - thanks for sharing.