On Sat, 25 Feb 2012 21:54:30 +0000, Roland Perry
wrote:

In message , at 21:47:58 on
Sat, 25 Feb 2012, Charles Ellson remarked:
I'm told about 1:10 proximity card transactions require a PIN. Whether
it's random, or by profiling the retailer/customer, I doubt is in the
public domain.

http://conversation.which.co.uk/mone...tactless-card/
refers to a PIN being used for any transaction over 15 UKP or any
taking the running daily total over 50 UKP.

£50 sounds a lot like "the average amount you'll run up before meeting a
random PIN check". Do any of the banks publish the algorithm?

Barclays themselves seem to present it as a random check but various
reports/reviews/etc. by third parties on an assortment of dates imply
a 50 UKP cumulative "trigger" which presumably does not need all
following transactions on the same day to be PINned unless they also
trigger any warning signs typical of fraudulent activity.