On Mon, 9 Mar 2009 03:50:41 -0700 (PDT), martin
wrote:

I've got a 16-25 Railcard, and intend to get a Z1-6 off-peak one day
travelcard, and then an off-peak day return to Bletchley. But should
this ticket be from Harrow & Wealdstone (the last calling point), or
Hatch End (the last station in the zones), or is a 'Boundary Zone 6'
available when travelling out of the zones?

Boundary Zone 6 exists for precisely that purpose, and is the one I'd
go for. The others require the train to stop at the changeover point,
so you'd have to use a slow train going back.

Neil

--
Neil Williams
Put my first name before the at to reply.