I remember coming across that site while searching some months ago, but lost track of the link. Thanks for posting it Hutch.
That page mentions that in the early days the Bakerloo had a negative outer and positive center rail, the opposite to normal, but there were some other difference stoo.
The Central line was built using a simple 3rd rail system with return via the running rails. The conductor rail was placed centrally between the tracks, not on the outside as in most other standard 3rd-rail systems. I believe the line was converted to London Transport's standard 3rd/4th rail system sometime in the late 1940s/early 1950s.
I read somewhere that one of the early lines (I think it was one which later became part of the Northern line) had two conductor rails, both placed outside of the running tracks (i.e. 3rd rail in usual position, 4th rail on the outside on the opposite side of the track).
I believe also that the power arrangements differ somewhat on the above-ground sections of lines which share tracks with British Railways SOuthern Region (or whatever company is running it this week!
). BR Southern used standard 3rd rail electrification with return via the running rails. Where London U/Ground trains share the tracks, I think you'll find that the central conductor rail is bonded to earth and the outer rail is the standard 660V positive.