A couple of weeks ago I wanted to do a day single to Leeds from York. To get the full discount using a railcard on a weekday the first train I can get is a Northern York - Blackpool North service, which of course stops at the intermediate stations and takes ages. However on this day a TPE Scarborough -Liverpool Lime Street service was late, and set off after 10.00 but was timed to depart before the railcard discount applies.
Therefore could I have went by TPE instead of the slower Northern service?
There are two sets of conditions which interact.
Conditions of issue and use of the 16-25 Railcard (formerly Young Persons Railcard) and reduced priced tickets ('discounted tickets') bought with a 16-25 Railcard
A £12 minimum fare applies for journeys made at or before 10am Monday to Friday excluding Advance Fares.
http://www.16-25railcard.co.uk/buy-16-25-railcard/railcard-terms-conditions
All the Standard Class Day Single York - Leeds fares are less than £12, so this means that Monday to Friday there is no reduction available before 10am with a 16-25 Railcard.
But it is likely that you were using an Off-Peak Day Single, so those conditions also apply.
National Fares Manual NFM 04 CD
From - YORK
To - LEEDS
Route - 00000 - ANY PERMITTED
Discount - 16-25 RAILCARD
CDS - OFF-PEAK DAY S TPE
1 Adult @£ 6.85
Standard Class Single
Restriction : B1
By any train except those timed to depart Mondays to Fridays before 0930
This means that it depends which Scarborough - Liverpool Lime Street service was late. If it was the 0940 from York running, say, 25 minutes late then that is valid. But if it's the 0840 from York running, say, 85 minutes late then that's
timed to depart before 0930, in theory it's not valid and on the train you may be asked to pay a 40p excess fare to make your Off-Peak Day Single into an Anytime Day Single. Railcard discount still applies.
I think it's most unlikely you would actually be charged, but that's what the rules say!
John