Graham J wrote:
No. PAYG credit does not expire.
I would have said the same about Bus Savers until recently.

Except that the credit on the old bus savers isn't expiring as such, you
just need to have the old tickets swapped for new ones.

Good. Initially, TfL said "The current design will no longer be accepted
on London Buses after 30 June, and we would advise anyone with spare
tickets at home to use them over the next four months as there will be
no refund or exchange of tickets."

See
http://groups.google.com/group/uk.transport.london/browse_frm/thread/c8a9ba9464ca1131/
where I suggested that this would be illegal.
--
Michael Hoffman