I don't think that will work. Shorthaul connections (and Domestic now I think) now book in J regardless of the longhaul fare bucket. At least this is the case ex-EU, I am guessing ex-US may be the same. Worth a try, but don't be surprised to see it offering J inventory with I longhauls.
I did not know that. Thank you.
There may be some other shorthaul candidates with I fares available - Spain, Portugal, south of France, Ireland, Turkey, Greece, Albania and the Balkans, Russia, Ukraine, Cyprus, Malta and the south of Italy. I fares must be available from these outstations for the POS method to work.
To save GBP 250 a ticket I think it is worth investigating each of these.