Mizter T wrote:

Technically speaking touching in even when using an Oyster card loaded
with a Travelcard that covers all the required zones is a requirement
when using NR. See the "Oyster Conditions of Use on National rail
services" (PDF):
http://www.tfl.gov.uk/assets/downloa...ional-rail.pdf

---quote---
3.6 When you use a National Rail service, you should touch your Oyster
card on the yellow card
reader before you start your journey, at the station you are leaving
from; and at the end of your
journey, when you arrive at your destinations station. You can still
use your Oyster card at
stations where there is no yellow card reader or if it is not working
provided that your
Travelcard is valid for the journey you are making. You may be asked
instead to show your
Oyster card (and photocard where needed).

And for those who are quibbling about 'should' rather than 'must' in the
above, I just found the following in the new TfL Conditions of Carriage:

http://www.tfl.gov.uk/assets/downloa...f-carriage.pdf

6.6. Using a season ticket on your Oyster card

6.6.1. When you use Underground, London Overground and National Rail
services, you must touch your Oyster card on the yellow card reader (see
clause 6.8.) at both the start and the end of your journey. If the
ticket gates at stations are open you must still touch your Oyster card
on the yellow card reader.

You can use the Travelcard season ticket on your Oyster card provided it
is available and valid at the time you travel and any pay as you go
balance on your Oyster card is not in debit. Should any pay as you go
balance on your Oyster card be in debit, you must clear the debit before
you use your Travelcard season ticket.

Provided that the season ticket on your Oyster card is available and
valid at the time you travel, you can still use your Oyster card at
stations where there is no yellow card reader or if it is not working.
You may be asked instead to show your Oyster card (and photocard where
needed).

and

6.6.7. When you use a bus, you must touch your Oyster card on the yellow
card reader (see clause 6.8.) as you board the bus. If you board the bus
without having touched your Oyster card on the yellow card reader or
having paid a cash single fare, you may be liable to a Penalty fare or
you may be prosecuted. Special arrangements apply if you are
accompanying a wheelchair user (see clause 13.2.1.) and to users of
double buggies (see clause 13.2.5.). If the bus has a conductor, when
asked, you must touch your Oyster card on the yellow card reader on
his/her ticket machine. If the yellow card reader on a bus or a
conductor’s ticket machine is not working, you must show your Oyster
card to the driver or conductor.