In message , at 12:22:48 on Sun, 6 Dec
2015, Roland Perry remarked:
Never seen a contactless transaction attempt declined.

I had to complete a contactless transaction as a chip & PIN
transaction once. The till operator told me this happens sometimes if
an invalid PIN attempt has been flagged for the previous transaction,
as was indeed the case.

I don't know if this would cause a subsequent contactless transaction
to fail if chip & PIN facilities aren't available.

If I remember, I'll try that tomorrow. All I need to do is put one of
my cards in an ATM and deliberately use the wrong PIN, then try to use
it on TfL.

I did the above, and the TfL gates accepted the card quite happily. So
it's not an instant-kill situation.

I've successfully used the card in an ATM, and on TfL, months ago, so
that may have established some sort of track record - for the card
rather than me or someone who had stolen it off me.
--
Roland Perry