In message , TKD
writes

I would imagine stations that already have barriers with Oyster readers in
place, that are currently only used for season ticket validation, would be
first. I wonder if they will let these stations go-live before the
equipment has been installed at the intermediate stations.

Its difficult to see how PAYG could work if some stations on the route
don't have readers - it would be a recipe for unresolved journeys.

--
Paul Terry