Originally Posted by
Oxon Flyer
If you happen to find yourself on a 321 on a domestic flight into LHR, it's likely this will be a mid-haul plane on a fill-in trip, so the chances of this being put on an international gate for its next flight is greater than for a 319.
I'd be surprised. I don't think the mid-haul A321s are used on domestics very often at all (if ever). Much more likely to be a short-haul A321 going on to PMI or VCE etc.