New York's Manhattan district and Monaco have continued to boom

The picture mirrors that of London, where average prices have been slowing in 2008, but the super-prime market has continued to see strong growth.

The fact London has enjoyed a boom in top end property in recent years has been well reported. Since September the prime market and the mainstream market have slowed, activity and price growth will slow further into 2008, but at the top end of the market there has been no such slowdown.

In New York developers are in a race to improve the luxury credentials of their property in order to secure a sale.