Official geographic Tube map
 

In message , at
08:45:43 on Wed, 7 Oct 2015, remarked:
I can't see anything called "Parkland Walk". Is this the feature you
mean: https://goo.gl/maps/7SuSjqD94sC2


Yes. It's a ventilation shaft (air - and not very nice air - is pumped
out through it). Some years ago they fenced it off and put up barriers
around it.

That would still be consistent with this route, which is the one most of
the mapping sites use:

http://www.perry.co.uk/images/finsbu...ria%20line.jpg
--
Roland Perry