If this is true, TfL are making it remarkably difficult for the public
to find out about it. There's nothing on the TfL or London Buses site
that I can see, and it's not in the fares leaflet. What was the form of
the "TfL publicity dated 24th December"? It's not in their published
press releases.

My local rag carried an advert last week with the banner "Money off" giving
the new bus and tram fares and the date of 27th February for the peak Oyster
fares. That's the only place I've seen it apart from on this thread.