"Roland Perry" wrote in message
...

If you know you are going in a loop, then you can buy a ticket from FP to
Cambridge; use the outbound half to Cambridge, then immediately use the
return half towards Liverpool St, but break your journey at Shelford.

But if you are then sold a normal Finsbury Park to Cambridge ticket, it
won't be valid coming back the other way, because it wouldn't include U23
validity?

....also, if the journey really is Shelford TO Finsbury Park as in the
subject line, that would require use of the outward portion twice...

Paul S