After the May completion date for full Oyster card integration came and went, South West Trains cited issues with Cubic, a third-party supplier of the reader Oyster card-reading chips and software.
Last week the Oyster readers appeared on ticket machines at Teddington station but are not yet operational so train users will still have to top-up their cards at newsagents.
These will be activated one station at a time throughout London SWT stations from the 26th of July. Ticket machines at Teddington are likely to be activated during August.
[Update] Oyster readers are now working on the ticket machines.