"Mizter T" wrote
So, for the sake of clarity, can we confirm that a 'Boundary Zone'
ticket can also be used with a *Day* Travelcard - as the 'Boundary
Zone' ticket is not in fact technically a separate ticket, merely a
receipt for an additional fare?

Yes, indeed I can confirm that. I do it regularly when I visit
London for 'leisure' (railway enthusiasm) purposes; I have often
bought more than one such BZ ticket on the same day. Sometimes I
extend 'normal' Day Travelcards; on other occasions I extend
'outboundary' Day Travelcards.

On Thursday this week, I used a Day Travelcard from Newark [1] and at
Victoria I extended it from BZ6 to Bognor Regis. Or at least that's
what I asked for at Victoria; I later discovered that I'd been issued
a Cheap Day Return from BZ*4* (rather than 6). Can anyone tell me
how much extra I paid because of this error?

[1] I drove to Newark because Cheap Day Returns and Outboundary
Travelcards are not available from Retford. NXEC: *please* do
something about this!