The real estate boom has added $1.5 trillion to the value of British homes over the past five years and left London residential property worth as much as Brazil's economy.

Research by estate agents Savills shows U.K. houses and apartments were worth £5.75 trillion ($8.7 trillion) in 2014, an increase of almost one trillion pounds since 2009.

London's stock of homes is now worth as much as Brazil's annual GDP -- $2.2 trillion.

The city's economy has rebounded strongly since the financial crash and that has been reflected in soaring house prices. They're up 61% in the last five years, and 20% last year alone, although there are signs that the pace is slowing.

The gains have been driven by a combination of stronger domestic demand and an influx of cash from wealthy Russian and Chinese buyers.

Properties in two of London's most expensive boroughs -- Westminster, and Kensington and Chelsea -- are together worth $345 billion. That's more than the GDP of Denmark, the world's 35th biggest economy.

While prices have been rising in almost every region of the country, the number of homes financed by a mortgage has fallen by 800,000 in five years. Younger workers are finding it harder to save the down payments and are renting in ever greater numbers instead.