Why would investor purchase commercial office in London and Hong Kong?

Please compare the commercial OFFICE property situation between London and Hong Kong. All the comparing data should be only talking Uk, London and Hong Kong, Especially Law Act.

1/ Short term and Long term investors in commercial OFFICE market

What do the investors look for in a short term and long term investment in commercial OFFICE property , e.g. different in expectation on yield %, capital growth, rental growth.
Differences between Long term and short term.
Long term look at the yield and capital growth (10 years & above)
Short term investment ( 3 yrs )

Talk about

Compare the term of the investment (duration)
Profit cash out
Liquidity

2/Risk management

Any regulation to protect the commercial office investors?
Compare the present situation of the Loan to Value (LTV), Property Gain Tax in Uk and Hong Kong (please verify that Uk do not have property gain tax on the commercial office)
How to protect the investors/purchasers?
Any commercial law Act to protect?
Regulate speculation? (Any law/regulations already/will impose)
UK and Hong Kong Law to reduce the bubble market?
Impact on future and current regulation Eg. Hot market, does government change the tax structure? Change the Stamp Duty?