On Wed, 8 Oct 2008, Barry Salter wrote:

Walter Briscoe wrote:
In message
of Sun,
21 Sep 2008 15:57:13 in uk.transport.london, Mizter T
writes
[snip]
(And I'm pretty sure that Marylebone NR and Baker Street LU are tied
together as being a valid OOSI, and I think this is also the case with
regards to Fenchurch Street NR and Tower Hill LU - though annoyingly
Paddington NR and Lancaster Gate LU is not an OOSI.)

Both true. As is Euston Square and Euston but not ES and Warren Street.
I've just been through to LU customer services and got one of the more
helpful members of their staff. They will try to assemble a list of those
interchanges. If they do, I will forward here.

I would've thought a fairly good place to start would be the list of stations
that are valid for cross-London transfer for National Rail ticketing
purposes, as that'll give a vague idea.

Do OOSIs affect Oyster pay-as-you-go fares? I do Finsbury Park - Euston
- Watford Junction fairly often, and i have no idea if i'm being charged
for two trips or one. I suppose i could just go and look at my Oyster
history!

tom

--
Understanding the universe is the final purpose, as far as I'm
concerned. -- Ian York