Hi,
To claim losses on the property disposal you will need to convert all figures from HKD to pounds sterling, using a just and reasonable exchange rate in use at the time of acquistion and disposal. Once all figures including costs are in pounds sterling, you follow the UK rules on calclating Capital Gains Tax.
Under the terms of Self Assessment, we do not provide an official exchange rate and the onus is on the individual to use a just and reasonable exchange rate for each acquisition and disposal. For your convenience, there are exchange rates here:
Exchange rates from HMRC in CSV and XML format
and for older rates here:
Foreign exchange rates and spot rates: 1 January 1989 to 31 March 2009
You are free to use any of the supplied rates or one of your own choosing.
Thank you.