Few people at home on UK's derelict billionaire's row

A third of the mansions on the most expensive stretch of London's "Billionaires' Row" are empty, including several that have fallen into ruin after standing almost completely vacant for a quarter of a century.

There are an estimated £350 million (HK$4.5 billion) worth of vacant properties on the most prestigious stretch of The Bishops Avenue in north London, which last year was ranked the second most expensive street in Britain.

One property owner, the developer Anil Varma, has complained that the address has become "one of the most expensive wastelands in the world".

The empty buildings include a row of 10 mansions that have stood largely unused since being bought between 1989 and 1993, it is believed on behalf of members of the Saudi royal family.

Their condition is so poor in some cases that water streams down ballroom walls, ferns grow out of floors strewn with rubble from collapsed ceilings, and pigeon and owl skeletons lie scattered across rotting carpets.

Most of the properties in the most expensive part of the avenue are registered to companies in tax havens including the British Virgin Islands, Curacao, the Bahamas, Panama, and the Channel Islands, allowing international owners to avoid paying stamp duty on the purchase and to remain anonymous.