"Paul Scott" wrote

An exception was allowed for Canada Water ELL, which is noticeably
sloping... the benefits of a cross-platform interchanange might have
allowed exceptions to be made elsewhere.
That isn't a true 'cross platform interchange' of the type being discussed
though, where the running tunnels are parallel, with through
connections...

But at least rigid insistence on level track at stations didn't rule out the
interchange altogether - I don't think the ELL platforms would have gone
ahead if they had meant rebuilding a considerable stretch of the ELL to
achieve a level section.

Peter