Sussex village to Farringdon £29.50 (anytime single)
Sussex village to Kentish Town £19.50 (anytime single)
As Farringdon is on the way to Kentish Town, and you can change there, is it possible to break the journey and leave at Farringdon?
My commute is to Farringdon, and this would help reduce costs massively.
Crazy that pricing is set this way
Fares to Farringdon can be charged at a premium as it's not a London Terminal and is an LU station. If your ticket has a cross-London marker then you are allowed to finish short there.
Fares to Kentish Town were probably originally set by the former First Capital Connect (FCC) company, who set fares much more reasonably than the old Southern company. It's now all GTR of course. GTR have adjusted some fares, which has included putting some fares down and others up. If this is brought to their attention, they may make amendments which would mean you'd no longer be able to pay as little as £19.50 for this journey.
I don't know how intently they read this forum; some people claim they cannot make any fares changes without DfT approval but I've not seen formal documented proof of this. In any case, DfT (who certainly read this forum) would certainly be supportive of amending the fares so that you would be paying a bit more in future.
Hopefully they won't notice this thread, or if they do, they may not be inclined to change it, but only time will tell....