Ah well thanks paul for confirming that... One thing I would LOVE to
know (to help my customers the best) is is the £4 charge 100%
universal (ie including zones A-D)? I ask because our posters say you
will be charged the "maximum cash fare" which, from Amersham for
example, is £6, not £4...

Any info you have will help to fill this small hole left by the info we
have received (which as usual forgets that we exist out in the country).