Just to add in another report: 3 separate US-issued AMEX platinum cards with contactless logo failed to work either at the Thames clipper ferry boarding gate or the London underground gate, despite being able to use it for conventional purchase. The gate at the tube gives out code 78, Card not accepted.

More interesting, at this page advertising contactless card for London buses,

https://www.americanexpress.com/uk/c...ments/tfl.html

It says "Look for contactless functionality to roll out to the Tube in the coming year."

No idea how long ago this page was setup.