From this afternoon's Q&A with SWT management:

Q. The Big Question: Oyster pre pay. Why was SW Trains not on the list of
operators getting ready to allow pre-pay on their routes and when will this
be resolved? The media suggested that you weren't satisfied by the support
TFL was offering, but I was left unsure of what was special about SW Trains
given that other operators could afford to implement the system this year.
Your unwillingness to join London's integrated transport is a major
headache - surely you should be providing the same level of service as those
operators on other routes?

A. The media was misinformed. We have never been anti pay as you go, indeed
ATOC (Association of Train Operating Companies) has been negotiating a joint
agreement on behalf of ourselves and all other affected train operators for
over a year. Nobody has yet signed this agreement. We expect to sign at the
same time as everyone else and introduce pay as you go at the same time as
everyone else. I cannot offer an explanation for the confusion created by
some elements of the media. We hope to all sign the joint agreement in the
near future, with pay as you go likely to come on stream in early 2010...

Paul S