BIG MACH,
As far as I know/understand the HMRC accept that UK based pilots( and UK PAYE) have to pay HKG tax and any tax demand from the HKIRD is being refunded to all that put in the paperwork. You also get a credit from the HKIRD for time spent in the UK. So even though it is a paper pain in the ar%e to do, you still only pay the total tax you would have paid to the UK tax man anyway, it is now being split.
I am only stating this for pilots that are living and paying UK tax, anyone else might have a different story.