Is it just me or is it reasonable to expect that all 1W carriers should be able to coordinate priority baggage accross the alliance? Is *A the only alliance offering such a service? Even if only for C and F pax, shouldn't they be able to deal with this? What's the point in Iberia tagging your bags as priority in BCN if, when they reach EI in DUB, they get bundled in with the masses in coach?
That said, perhaps tagging transfer bags as priority when going thru LHR would just be more of an incentive for those talented and skilled BA baggage handlers to send ones belongings off in to the wild blue yonder...

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Come on 1W - we're not asking much!