So, here's how ORC played out for me:

Original routing was DUB-LHR-JFK-LAX-HNL.... ticked by AA, mostly AA codeshares, crediting to BA, 3 passengers on the same itinerary.
After a ground hold at DUB, missed a connection in LHR so actual routing was DUB-LHR-LAX-HNL.... The return journey went fine.

Dec 27 2017: Rebooked in LHR, flights all flown to LAX, then to HNL the next day. Big Island (via a separate Hawaiian AIrways ticket) as nice as ever.
Feb 18 2017: ORC credit submitted to BA customer service via their web form, with full details, case reference received.
end Feb 2017: reminder sent to BA CS, still no response.
March 8 2017 21:00 GMT: PM sent to BAMissingAvios with a copy of the details and the BA case reference.
March 9 2017 14:00 GMT: PM received from BAMissingAvios showing understanding of my claim and promising investigation.
March 19 2017: progress inqury sent to BAMissingAvios
March 20 2017: polite response of "still working on it, AA has to look into it particularly because one of the flights was marketed and operated by them" from BAMissingAvios,
March 22 2017: Response from BAMissingAvios confirming Tier Points and Avios for the original route.

Result! That should put me at BA Gold for my next long trip, which will be useful since I want to enjoy both the LHR T5 and AKL First lounges

So BA CS were not useful, but Flyertalk and especially BAMissingAvios were extremely useful.

Now, off to fill in a ba.com/welldone for staff member D.... behind BAMissingAvios.