Upvote:5
In theory, no:
Break of journey is not permitted except to change trains
Finishing your journey short at least used to count as break of journey (not sure this is still the case any more, I think it's ambiguous since the transition from Conditions of Carriage to Conditions of Travel. Reading the section in question I certainly get very confused as to whether finishing short is supposed to count as a break of journey or not. I get the impression that MAYBE they wanted to cover starting late as BoJ but not finishing short, which would mean you could only use it in one direction).