World class cities not only attract international business, they are also the haunt of a growing number of global billionaires who are increasingly important investors in residential real estate and their wealth is creating a new global super class of real estate, according to new research.

In the top ten cities real estate values have increased by 10% in first six months of 2011, the latest Savills Research global billionaire property index published today (Wednesday September 21) shows.

Hong Kong is in a league of its own in value terms with property worth £6,700 per square foot, an increase of 83% from December 2005 to December 2010 and a 10% increase on top of that to the end of June 2011.

In second place is Tokyo at £5,190 per square foot, followed by Paris at £3,270 and London at £3,090.