I’m not sure I agree 100% with idea that short haul leisure base at Gatwick existed or exists for those reasons, especially with the much expanded leisure route network ftom Heathrow. The two class cabin is differentiator imperfect as it may be. Fares wise BA do seem to be challenging other carriers. I continually compare EasyJet and BA when making my travel plans and BA is competitive. I agree this is not the same as assumptions regarding profit. However BA do seem keen to keep their short haul presence at Gatwick and plan to expand it. Knowing their obsession with costs I doubt they would continue to pursue if situation was hopeless.
I do know from various contacts that flights are often full in all cabins including the A321s.I understand that may not relate directly to yield but there is a demand there.