Scenario: a friend of mine from Dublin was coming across to do the
London Marathon and asked me what ticket he should get. He was
arriving at Heathrow, then had to go across London to Custom House to
pick up his marathon stuff. He then had to come back to Leicester
Square to meet me for dinner, then we were heading back to New Cross
afterwards. All tube or DLR journeys apart from the very last one,
which was on National Rail.

Mindful of the fact that Oyster prepay doesn't work on NR, I told him
to get a one day travelcard for Zones 1-6 at Heathrow. As you can see,
I didn't realise that you can't put one day travelcards onto Oyster!

Result: my friend's journey goes smoothly until we get to Charing Cross
to catch the New Cross train. He's not allowed through the barrier and
the guards just keep yelling "Prepay is not valid on National Rail",
without explaining the one day travelcard issue (we were protesting
that he had a travelcard).

I now understand why it didn't work, but have some questions:

1. What was my friend sold at Heathrow when he asked for a Zone 1-6 one
day travelcard to be put onto his Oyster card?

2. Would he have been able to buy a paper ticket at Heathrow for the
same price, thus being able to use National Rail on a one day
travelcard?

Patrick