longest walking distance between lines

My first guess would be Jubilee to Bakerloo at Waterloo, but some of the walking routes at Bank are convoluted so they may be longer.
Not the Underground, but Eastbound TfL Rail to the Overground at Romford is a not insignificant walk.

Except that the most direct route from W&C to Circle line platforms doesn't involve the travolator - or it didn't until they closed the direct connection in order to build the new entrance on Cannon Street - after which the most direct route from W&C to Circle line will be the OSI !

In my head I have that Bank/Monument is one station with two names.

Has to be, logically, a station with most lines in it, which would have been added at various times and various depths, long before step-free access.

King's Cross, Bank & Euston spring to mind, not to mention Paddington. All were also originally in the Tube fold to serve as destinations, rather than as interchange stations, which might explain a lot.

The only 'one' I ever did a pedometer on was Piccadilly to District at Aldwych, which is cheating, because Temple is 640 yds down the road from Aldwych station entrance!

I suppose thats largely because it was two stations originally. This then begs the question of maximum radius/walking distance considered before two stations are deemed acceptable as interchanges. As I'm (predictably) in the pub and not in the best condition to do so, perhaps some of our more studious (and sober) members would be able to work out the qualifying candidates? 

I read the question as not going out of a station.eg not passing through a card reader. The Waterloo run is a bit of a schlep as is the W=C to DLR
Not done any KX changes yet but from what i have seen on here and other sites they are horrendous.


So are there any rat runs that the great unwashed can use legally to shorten any treks?

Without passing a card reader - Waterloo (Bakerloo to Jubilee), Green Park (Piccadilly to Jubilee) and Charring Cross (Bakerloo to Northern) feel the longest. King's Cross (Northern to Piccadilly via the new passages) is long but not as long I don't think, and is easily avoidable if you know to use the south end of the Northern Line platforms. Indeed, ignoring the signs is often the best way to get around King's Cross (at least as long as most people don't).