Plusgrade is a Canadian (Montréal) company that has quite a presence in the world of Star Alliance, cruise ships and things like upscale rail travel. They are a respected operator and the key point here is that unless Plusgrade can get the upgrade, they won't get paid.

So it looks here that IAG is trying to leverage upgrade revenue from multiple sector bookings, which are hard for their own IT service, but which can be outsourced - on a revenue share basis - to an external company. Plusgrade does the heavy lifting, and - the critical bit for Tier Point chasers - they reissue the ticket into the higher grade as opposed to adding a sticker to an existing coupon. Same happens with most of the Star Alliance, though it is complicated there by the inconsistent approaches to frequent flyer schemes within Star.

It poses the question why BA can't do this for same metal journeys too, since they can't normally get an POUG offer.