[ColinWright]

Don't they all just work on published walk-up fares? My system also uses advances fares and relevant return and/or single journeys. I've never found an app or web site that uses the full range of options available.

Probably because (as I've discovered) it's hard.

[zimpenfish]

Private Eye often have bon mots about how even the ticket offices don't offer people the cheapest ticket because they can't figure it out.

But when you have to deal with things like (eg, I'm hope I'm remembering this right from someone I know) "EUS-CDF being more expensive than EUS-SOT + SOT-CDF even though both halves are the same train as the EUS-CDF journey", you can see how no-one has a bloody clue.

[rahimnathwani]

Don't they all just work on published walk-up fares?

I must confess I've never used the app. I just read about it in the MSE email newsletter.

I grew up in London, and didn't often have reason to take a long distance train. I have a vague childhood memory of discovering that London and England weren't synonymous.