The removal of 31 (I think it was) 747s from the long haul flying programme during covid was a big step change in long haul flying, which will now be being recovered as quickly as BA can get their hands on new long haul aircraft. Many A320 captains are therefore obtaining moves to long haul, and the seats they are vacating need filling - resulting in the current very junior A320 commands. At the same time, the end of 2023 also sees the end of the NAPS P2 to P1 transition capability, and so larger than normal numbers of long haul SFOs have bitten the bullet and taken short haul commands so they do not miss out on the pension uplift. I suspect far fewer will do so in 2024, and so I predict the large numbers of P32L to C32L conversions to continue into 2024. That being said, it is difficult to know how many current A320 FOs are kicking themselves for not bidding for commands in 2023, and will not repeat the mistake in 2024.
Predicting seat change seniority is complicated, and just one year to a Heathrow command is very much an extreme covid induced abnormality at the moment, which should not be relied upon. How long it will last is anyone’s guess.