Any passengers who did LHR-AGP but refuse to leave the plane in AGP do not want any passengers to board the plane in AGP as everyone would then have to quarantine in the UK. I assume that anyone who is not going to the UK within 14 days (such as people from Gibraltar going home) accepts to deplane in AGP and that those who remain are those who do not wish to quarantine.

I'd imagine that any passengers who have booked GIB-LHR-XXX where XXX is outside the UK can take a bus to AGP and board a flight there. However, if they were to board the BA flight going back to the UK, those who remain on board would be furious. If the passengers are to be transported to AGP, then I think it is better to rebook them on a different flight, for example VY2120 (dep 17.10) or VY2112 (dep. 19.30) to BCN, BA455 (dep. 20.25) to LHR or IB8951 (dep. 21.30) to MAD if they want to keep it within IAG. I assume that the diversion delays the passengers so much that they miss their connections at LHR no matter which flight BA rebooks them on, so the connecting flight from LHR to XXX needs to be rebooked anyway.

It seems that BA491 departed AGP more than four hours late.