A note of caution, on Thursday, I went from Lewisham to Canary Wharf using prepay on the DLR. Touched in my Oyster card at Lewisham and on getting off at CW, got to the bottom of the escalator to leave the station where a ticket check was being conducted by Serco staff, which was fine, BUT forgot to touch out my Oyster card. It cost me ?4 for an uncompleted jouney, I then had to phone DLR to get the refund. As an infrequent user of the DLR they will be sending out a cheque. Would be more useful to have the Oyster touch in/touch out machine on teh platform. So if you use prepay, lesson learnt was not to forget to touch in and out. Rant over.