PS just make sure you have a good resettlement package as real estate is expensive, especially where you will want to live whilst you settle down. Most of the ex pats converge around Mid Levels/Robinson Road area on the Island to begin with as it is near the action and the Financial District.
rents are expensive but most employers (even the school my Mrs's mate went to) seem to help with accommodation costs to begin with and when you are paying full whack yourself you'll prob want to move a bit further out on the Island (or Kowloon side if you fancy that)
other thing is getting paid in £'s, definitely check how that is going to work for you as it is much less favourable since our currency tanked and make sure you are on a UK T&C's as HK contracts get chuff all holiday, something like 10 - 15 days a year, although they do have more public holidays.
now my mate is a resident and freelance in his field, he gets paid in HK$ and is something like 15% flat rate tax iirc, which i think he finds a bit of a touch..
he also used to get two return tickets home a year - which involved going in to an office for like a day to show his face but then see family etc, but i think those days have probably gone by now.
one last thing, i wouldn't go if you are rubbish at making friends, but i guess you have already emigrated once so that you know