Homeowners in London's richest neighbourhoods are racing to build luxury basements with pools and wine cellars before new rules limiting underground developments come into force.
A rising number of property owners unable to build upwards or outwards in tight London streets have opted to dig down, bypassing rules governing above-ground work.
Tetra Pak heir Hans Rausing this week won approval to build a pool, cinema and cigar room under his London mansion - the same home where his wife's body lay hidden for two months last year after her drug-related death.
Chelsea Football Club owner Roman Abramovich, Formula 1 heiress Tamara Ecclestone and steel tycoon Lakshmi Mittal are among those who have also dabbled with basement extensions.
A spokeswoman for Kensington and Chelsea Council - where semi-detached houses cost an average £6.1 million (HK$74 million) - said a record number of applications had been received this year.
In the first five months the council received 166 basement applications, compared with 297 in all of last year - a sharp contrast to 2001, when 46 basement applications were submitted.
But the Kensington and Chelsea and Westminster authorities, most affected by the basement boom, are now finalising stricter rules for subterranean work in response to anger about the disruption and structural impact.
Final comments on the plans were submitted this week and they are expected to come into force early next year.
Residents' groups have been angered by extensions causing noise and disturbance during construction. They have also given rise to traffic problems, vermin and the fear developments will affect the structural stability of neighbouring buildings.
"There were just no rules and we've had quite a few accidents, such as a skip [a large transportable open-topped container for building refuse] cracking through the street and water leaking into neighbouring properties," said Randa Hanna, of the Belgravia Residents' Association.
"There has been an astronomical rise in the number of basement developments, many of which were not monitored properly, and introducing some rules is a step forward."
The new rules will make major basement extensions more difficult, as excavations deeper than one storey will be allowed only in exceptional circumstances and basement extensions covering more than half of the garden will not be allowed. Developers expect other councils in London to follow suit.
"This summer we've seen people rushing to get consent for basement developments," said Charlie Bubear, of the Chelsea office of Savills real estate agency.
"This can add significant value to a property. Basement conversions are the only way to go if you want to extend and it avoids the costs of having to move. But you can understand resentment to living next to a building site."
Bubear said it costs about £500 per sq ft to build a basement, but properties in the area sell for up to £2,500 per sq ft with big price rises annually.
Hanna said the new rules should slow the pace of basement developments, but would not stop it altogether. "It is too much to say you can't build in your own home," she said.