Here's a map of bank station (central line) as it used to be:
http://homepage.ntlworld.com/clivebi...ankSubways.jpg

The lifts used to go straight to the platforms, and the remains of the
shafts for two of them are still there - converted to spiral
staircases down to the northern line.

But if you look at the map, there's a fifth shaft, out of line from
the others. Wouldn't that be right on top of the tracks?