Originally Posted by
Prospero
I am hesitant to put forward a black and white answer. In my experience, which relates exclusively to trips ticketed from EDI to short haul European destinations and booked in discounted economy, none of these tickets were eligible for POUG. This, I have been told by BA, is due to the rules that apply to these specific fare combinations, with emphasis on the adjective specific.
I think if any POUG proposition is going to be made available to a ticket containing UK domestic feeders it may be those with a fare combination that work within the existing MFU mechanism. Thus, in theory, a EDI-LHR-SFO booked in T class with domestic sectors booked in J may well be eligible for POUG (subject to availability). Whether MMB has been primed to offer this is a different issue.
Just my musing on the subject.

Mr H travelled MAN-LHR-BOS in J domestic, T transatlantic but was not offered an upgrade on MMB. Several people were op upped WT+ to CW on the flight, but not him.