When a $5m Georgian townhouse in Barnes, West London collapsed last month during building works local residents were quick to lay the blame on the construction of a gigantic basement below the historic six-bedroom property, which was set to include a cinema room, an entertainment area, a gym and a laundry room.

The developers have insisted that the collapse was simply due to the property being an ‘old building’ and was unconnected to the gigantic ‘iceberg basement’–the nickname refers to the way a large portion of an iceberg is underwater–they are digging, but their arguments have largely fallen on deaf ears.

The spread of gigantic basements are a lightning rod issue in London these days, pitting neighbors in some of the capital’s leafiest streets against each other.

The collapse of the historic house in Barnes—which displayed an English Heritage plaque in honor of the fact that it was once lived in by Ebenezer Cobb Morley, a founder member of the Football Association who wrote the rules of modern football—has proved the latest focal point for the increasing anger at the rising trend for basement extensions in London.

In the UK capital, planning law often forbids houses from being extended upwards, forcing millionaires to burrow into the London clay in their quest for more square footage.

Prime examples of the trend include the basement dug by Britain’s richest woman, and a basement development by the multi-millionaire founder of Foxtons estate agency, Jon Hunt, who was recently granted permission to build a massive underground extension to his home, including, mind-bogglingly, a tennis court and a car museum.

Hunt’s extension, five stories deep, would not be permitted under new planning law in London’s posh Kensington district which restricts basements to a single storey.

John Caudwell, a British retail millionaire, is creating a monster basement connecting his main house to the mews house at the end of his garden, which he also owns.

In perhaps the most extreme example of basement mania, the ground underneath a London mansion block was recently sold for £150,000 at auction as an ‘unexcavated basement’.

Neighbors get particularly furious at basement extensions because the sheer scale of the construction—which begins with the excavation of thousands of tonnes of earth—means they are more disruptive than regular building. They also fear the works will affect the structural stability of their own house.

Matthew Bell, an editor at British society magazine Tatler told the Daily Beast, “I lived on a nice leafy street in Chelsea, and one by one every house on the road was bought up and basements were built. The noise is just incredibly annoying.

“As a Londoner you are used to noise, but it’s relentless drilling. You can’t hear yourself think, it’s really intrusive. And the irony is that a lot of the basements actually go unused. They are dark and dingy and oppressive and you would not want to spend a lot of time down there. A lot of it is willy-waving–‘mine is bigger than yours.’”

In many instances, the super rich plonk their staff quarters in the basement extension, Bell says.

The guitarist for the band Queen, Brian May, has been a particularly vocal opponent of the trend, recently telling his local paper: “I’ve suffered for about seven years now, initially from the construction of three basements on my road, but there are about to be more.

“You might think, ‘What’s a little bit of noise?’ but you’re talking about a three year period of these people making this noise six days a week! Your house isn’t safe, there’s nowhere you can get away from the noise, even with triple glazing, and you end up being angry all the time, because you’re under constant stress.”

Scott Goldstein, a solicitor at Howard Kennedy who tweets as @basementlawyer, told the Daily Beast that the disruption is only part of the story why these developments fuel such resentment.

“The projects do also seem to symbolize a certain way of life, the ‘Notting Hill set,’ and people cotton on to that.” he said.

“Structurally, the mass development of basements on the scale we are now seeing--hollowing out huge areas of ground--is a new phenomenon, and the law is struggling to catch up with the trend. I have no idea why [the house in Barnes] collapsed but the thing about basement developments is that when they go wrong, they tend to go fabulously wrong.”

Matt Brereton of Chestertons estate agents said, “Basement extensions are a growing trend, but they can quickly go wrong, if not done correctly. It is roughly three times more expensive to develop a cubic foot underground than above ground. So we advise people to be sensible and conservative, and exhaust all other options first.

“They are expensive to build, but with prime central property now exceeding £1000 (around $1522) per sq ft, the rewards are enticing. But a shoddy job can undermine the value of a house—not just its foundations.”