UK tax - me know very little!
I can't comment on how the mechanics of it all will work but I can comment on the generalities.
UK basing company will start early April 08. Anyone working for that company will therefore be liable for NHI and normal UK income taxes. Residency or not is beyond my knowledge so for that you will need professional advice. Double taxation agreements prevent 'double taxation' ie you will pay the total tax of the higher taxing jurisdiction (UK presumably). But that does NOT mean in the short term you may be double taxed and have to claim the over taxation back from either authority.
CX were trying to get HMRC to accept a lower rate of tax due to 16% tax in HKG. I don't know if they have been successful or not.
So, worst case, you will be taxed normal tax in UK plus 16% in HKG. When you eventually show your tax receipt for HKG the HMRC should refund you the 16% you paid in HKG.
Clear as HKG water?