not sure best place to post this: anyway interesting 1987 memo from the commissioner of rating and valuation to the secretary for the civil service about how much to charge for government properties. Gives dates of construction for all of them, plus some vivid descriptions ...
http://www.jsscs.gov.hk/reports/en/18/report/r18_eng_appendix_vii_annex_k_1.pdf
this seems to be part of the Jones Lang Wooton report the commissioner seems to disagree with: http://www.jsscs.gov.hk/reports/en/18/report/r18_eng_appendix_viii_annex_f_3.pdf
looks like full appendix is here: http://www.jsscs.gov.hk/reports/en/18/