Matthew Dickinson wrote:

Prepay is valid between:

And my guess at the reasons for each.

Moorgate - Finsbury Park

i.e. the old Great Northern & City line that used to be London Transport. Or
more realistically because of:

Kings Cross - Finsbury Park

Dpulicates the Victoria & Picadilly lines.

Kentish Town - Elephant & Castle / London Bridge

Thameslink in the central zone I presume... Am I right that PrePay is
available at City Thameslink?

Richmond - Gunnersbury

Which uses the same tracks as the District Line.

Euston - Harrow & Wealdstone (not valid at Kilburn High Road or South
Hampstead

Basically the same tracks as the Bakerloo Line, plus allowing direct access
to Euston rather than everyone changing at Queen's Park and again at Oxford
Circus (which isn't laid out well for this kind of interchange).

Liverpool Street - Walthamstow Central / Seven Sisters / Tottenham
Hale (not valid at any intermediate stations)

I can only guess this is to do with the Victoria Line, but is this really a
duplication?

Liverpool Street - Stratford

Duplicates the Central Line.

Stratford - Canning Town

Duplicates the Jubilee Line.

Fenchurch Street/ Liverpool Street - Upminster via Barking (not valid
at Maryland or Forest Gate)

Duplicating the District Line and, more rarely, the Hammersmith & City (plus
a bit of the Central). Annoyingly Forest Gate is my local station.

Marylebone - Amersham

Duplicating the Met plus allowing the London terminal rather than have
everyone changing trains at Harrow on the Hill to arrive at a very nearby
station.

Marylebone - West Ruislip (only intermediately at South Ruislip)

Similarly with the Central Line I guess, although the Marylebone to South
Ruislip section isn't really duplicating the Central in a meaningful sense
or going to cause bizarre interchange habits is it?