Mayor refuses to heed Assembly calls for crackdown on ‘iceberg’ homes

mega-basement desires?

mega-basement desires?

It has emerged that the Mayor of London has ignored a unanimous call from the London Assembly to establish planning policies to prevent inappropriate basement development.

The cross-party Assembly passed a motion in March calling on the Mayor to introduce such a policy into his London Plan, but in response, the Mayor has informed the Assembly that he does not consider it necessary to introduce new rules.

Subterranean development is a growing issue in some parts of London, including Kensington and Chelsea, Westminster and Camden boroughs. Increasingly, the super-rich are digging deeper and wider in an effort to cram swimming pools, cinemas, and gyms into often historic buildings, creating so called ‘iceberg’ homes. These developments can cause flooding, sink holes and structural damage to neighbouring buildings, and construction is often severely disruptive to the neighbourhood.

The worst-affected boroughs have policies to limit inappropriate basement development, but without the backing of a strong policy in the London Plan they will may find it difficult to enforce and can see their decisions overturned by inspectors.

Murad Qureshi AM, who proposed March’s motion that received unanimous support, said:

“I find it astonishing that the Mayor is flatly refusing to stop the growing problem of subterranean development in the capital.”

“Despite the Mayor’s claims that supplementary guidance gives individual boroughs the backing they need to prevent inappropriate basement development, it is clear that these rules are just not strong enough.

“The London Plan presented the perfect opportunity for the Mayor to help curb this growing problem, but by rejecting this motion he has ignored the views of every single member of the Assembly.” 



  1. Murad Qureshi  AM is a London-wide Labour member of the London Assembly.
  2. The London Plan is the spatial planning strategy for London. The draft Further Alterations to the London Plan were published 15 January for consultation concluding on 10 April. The alterations can be found here:
  3. Most local authorities have planning policy on basement development but four of the boroughs where the problem is most acute – LB Camden, LB Haringey, RB Kensington and Chelsea, and LB Westminster – have or are developing special policies to tackle it.
  4. The full text of March’s amended motion read: “This Assembly notes that inappropriate basement development is an increasing problem within London. In the Royal Borough of Kensington and Chelsea, for example, planning applications for basements rose from just 13 in 2001, to 182 in 2010, and to 307 in 2012. Some of these renovations are turning already-large homes into massive iceberg houses, and can cause flooding, sink holes and structural damage to neighbouring buildings. Despite the rising concern, the draft Further Alterations to the London Plan (FALP) does not include a specific policy on subterranean development. Although draft Supplementary Planning Guidance and the current policy on sustainable design and  construction require consideration of some issues, London must adopt      stronger policies to help boroughs prevent unnecessary basement  development, such as prohibiting extensions under listed buildings and limiting the size and depth of new and redeveloped basements. This Assembly therefore calls on the Mayor of London to revise the FALP to include a specific policy against inappropriate basement development.”
  5. The Mayor’s response to the motion can be read here (Motion 4) “At this stage, I do not consider it necessary to include a specific policy in the London Plan restricting basement development. My emerging Sustainable Design and Construction Supplementary Planning Guidance encourages boroughs to develop local policies, where required, and I have already used this strategic position to actively support the Royal Borough of Kensington and Chelsea in developing local policy to protect against inappropriate basement development in light of its local circumstances”



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