In message , at 09:00:46
on Mon, 25 May 2015, remarked:
I'm taking my definition of "London" as what's shown on TfL's map of
"London rail and tube services" (see the thread title).

Zones beyond 6 are only there to allow Oyster to work outside Greater
London. Are you asking for Oyster zones all the way to Bishop's
Stortford?

No, just for the stations on the "London rail and tube services" map
to be generally understood as being in London.

You say. I doubt they would agree with you in Hertfordshire.

The stations in question are inside the green belt (although some might
say anomalously so).

http://londongreenbeltcouncil.org.uk...gbmapleaflet15
..02.15.pdf
--
Roland Perry