In message , Ian F.
writes

Still not sure it's of much use to me. I travel a few times a week from Zone
3 into central London, an occasional bus ride, and a few Southern trains
between Balham, Victoria, Croydon etc., on which I understand you can't use
Oyster.

Would there be any point in loading a one day Travelcard (say zones 1-4)
onto an Oyster card on a day when I need it, or might I just as well carry
on buying paper tickets?

As others have said, you cannot load a one-day Travelcard.

If you have Oyster pre-pay, fares at Oyster rates will be deducted and,
if your daily total exceeds a one-day Travelcard, the Oyster will give
you the benefit of the total being capped at one-day Travelcard level.

However, without more detail of the specific journeys (especially how
you get from Zone 3 to Central London), it is impossible to say whether
or not you would be better off.

IMO, Oyster has little to offer significant numbers of Londoners until
surface rail is brought into the scheme.

--
Paul Terry