Out of interest, what's the situation if one attempts to purchase a travelcard with a railcard discount? I used to try to buy my travelcards a couple of days in advance when I commuted to uni, as I needed to catch a bus to get to the station in the morning, necessitating that I had the travelcard on me when leaving home. South West Trains and NXEA were always happy to sell me the tickets, but South Eastern always said they couldn't except for one specific clerk at New Cross. If I recall correctly, they said that I couldn't buy them in advance because of the railcard, hence the question.