"tim....." wrote

OOI what is this railcard that attracts a discount based upon ticket type
and not an absolute time restriction?

Senior Railcard. It's technically a time restriction, but in the Network
SouthEast area Senior Railcards can't be used until Off-peak tickets kick in
for the journey being made - so the kick-in time varies according to the
journey.
http://www.senior-railcard.co.uk/eli...-travel-times/

Peter