“We’re probably walking above someone’s swimming pool now.”

Roger Burrows has become used to walking on “icebergs” on dry land.

In many areas of “super-prime” London, where the city’s super-rich have their homes, planning restrictions and conservation guidelines mean you can’t extend your property laterally or add floors on top.

The solution? Dig down.

Burrows is a professor with the School of Architecture, Planning and Landscape at Newcastle University, UK, and first realised what was happening during a research trip to Regency Drive in South Kensington, London.

“We’re talking about sometimes gargantuan excavations led by mining engineers digging many, many metres down, sometimes digging out across the envelope of the house into the garden,” he told ABC RN’s Return Ticket.

Researchers classify basements by their size: standard, large and mega. Some of the largest builds reach 18 metres deep and are larger than the home above ground – hence the nickname icebergs.

You’ll find basements like this across a swathe of London, from Kensington and Chelsea through Westminster, coming up into places like Highgate and Hampstead.

Burrows and his co-authors collected data on London basement construction projects from 2008 to 2019 and mapped it, publishing the results in Bunkering down? The geography of elite residential basement development in London.

They found an astonishing 7,328 basement additions had been built in just over 11 years. 

Inside the iceberg

With rich owners shrouding their basement builds in secrecy, studying council plans is what allowed Burrows to curate a long list of things you can find in these luxurious basements.

There are swimming pools, gyms, cinemas, car museums, Turkish baths, saunas and spas, staff accommodation, panic rooms, golf simulators and wine cellars. They even found one with an artificial beach.

To call these projects basements might be considered misleading – real estate agents prefer the term “lower ground”.

A basement implies a dank, dark space, and these luxury levels are anything but, boasting high ceilings, skylights, luxury finishes, expensive fittings and artwork with eye-watering price tags.

Alan Waxman of design studio Landmass London and self-anointed “basement king” reportedly designed one home with Nicole Kidman in mind, which featured a 34-foot waterfall. (She didn’t end up moving in.)

“People say my properties are a bit like the Tardis in Doctor Who,” Waxman told a BBC documentary crew.

“It looks very conservative or conventional from the outside, but when you walk indoors it is like going into a different world.”

A plague of basements

Burrows traces the basement “epidemic” back to 2006–2007 and estimates that a huge volume of soil and clay, something like the volume of 12 times the interior of St Paul’s Cathedral, has been extracted from these parts of London in the last decade alone.

Shifting that amount of earth hasn’t been without its logistical challenges: construction crews have stumbled across underground rivers, chalk mines and even unexploded World War II bombs.

Still, enough people have persisted that hundreds of diggers – compact machinery used to excavate soil – are now entombed below these basements. At £5,000 or £6,000 a pop, they’re said to be cheaper to bury than to extract once you’re done digging.

But as the earth has been hollowed out beneath these homes, neighbours say the incessant noise pollution, repeated flooding and structural damage to their homes has made life very difficult.

It’s no wonder such homes can now cost in the range of £20m – or that the neighbours hate them passionately, alleging construction is “absolute hell”.

“The owners won’t mind because they, of course, won’t be there,” wrote Julian Lloyd Webber, British solo cellist and broadcaster. “Move into a building site with all that noise and dirt? Don’t be ridiculous!”

Elsewhere, botched basement extensions have led to scenes like “something out of a disaster movie” as family homes have cracked in half, and basement excavations have led to 5-metre holes opening up on the road in front of some neighbours’ homes.

In July 2021, after a nice day at the Royal Holloway College, Queen’s guitarist Brian May came home to “horror in our house”.

In a video posted to Instagram he gave his followers a tour of the bottom floor of his house, covered in “black sewage and sludge”.

Read the rest of the story here. First published by the ABC on July 12.