The Hainan flight often arrives at an ungodly early time, occasionally as early as 4am but regularly 4.30.
Tranferring passengers have to change terminals and then wait for transfers to open at 6am. There are only usually around 12/15 transfer PAX's per flight and most of them transfer around the UK.
It's got to be a bit of a put off for some PAX's following such a long flight. Perhaps something Hainan might look at in the future.