Richard J. wrote:

But that old post of mine that you discovered (full marks for detective
work!) was sent in October 2005, and the bit about the lack of advice
from TfL is no longer true. Since September 2006, the TfL fares
leaflets have included advice to check for the green light. The January
2007 edition says "Please check for the green light when you touch in
and/or out to ensure that your Oyster card has been validated. Failure
to touch in and/or out may result in a penalty fare or you being
prosecuted."

Is everyone supposed to read the small print in the fares leaflet every
year?
--
Michael Hoffman