In message , at 17:13:22 on Sat, 25 Feb
2012, tim.... remarked:
I don't think he is right in saying that there are some routes with "+HS1"
tickets

Kent-issued outboundary Travelcards, specifically.

(as in a single main ticket, not an add on) but as I (obviously)
haven't checked all the possibilities there might be.

But if there is, the same rule would apply that the +HS1 is only applicable
to the single through journey to/from Ebbsfleet to London and would be valid
to either StP for Stratford for one single journey (per direction of
ticket).

The "only one journey" rule applies to the part outside the Travelcard
zones, once inside you can make as many journeys as you like (modulo the
possibility that even the semi-mythical +HS1 Travelcard might be invalid
from Stratford to StP.

Though one thing I don't know (and have been meaning to try for ages) is,
can I break my journey at Stratford (to visit the shopping centre) and then
continue later to StP (which would be my intended destination whenever I buy
super expensive ticket)?

If it's a CDR on HS1, then it should allow BoJ.
--
Roland Perry