In message , at 06:33:49 on Thu,
3 Mar 2016, Mike Bristow remarked:

There is, perhaps, an interesting debate to be had about how close
two platforms can be to count as an interchange; my suspicion is
that Forest Gate / Wanstead Park are close enough for any sensible
gap - if they're not, then interchanges between the Central Line
and Northern at Bank probably don't count either.

I was surprised how far it was from Bow Road to Bow Church. About 300m,
and also in the opposite direction to the way it's depicted on the tube
map.
--
Roland Perry