Fears Hampstead mansion plans set ‘dangerous’ basement precedent

Permission for a “ballooning” basement extension to a tycoon’s �9.1million Hampstead mansion could open the floodgates for other controversial underground works, it is claimed.

Camden Council approved plans last week for a basement in Templewood Avenue which dwarfs the footprint of the original house.

Cllr Matthew Sanders, who sits on the planning committee, said the size of Geneva-based Trifon Natsis’ underground development contravenes council planning policy and sets a “dangerous precedent” for future basement proposals.

Plans for a swimming pool, gym and pilate’s room – under hedge fund boss Mr Natsis’ London retreat – will see the basement more than double the original floorspace of the house to 495 square metres. Cllr Sanders, who chose to abstain from the vote, said: “Basements are a massively controversial issue and here we have something that just balloons outside the building’s footprint despite our policy.”

He added: “We have to be very clear that we’re applying policy fairly and equally because we’re bound to get more basement extensions in the future.

“If we’re going to bend the rules we need to be clear that we’re not going to do it for every application.”

Conservation groups challenged the plans, branding them “non-compliant” with the council’s guidelines.

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Gordon Maclean, chairman of the Heath and Hampstead Society’s planning sub-committee, said: “It seems to be a departure from their policies and I would like to know why they would agree to that. We have been extremely worried about the extent and number of basement extensions in Hampstead in recent years.”

A legal officer for the council said: “If it goes beyond the footprint there is quite a high threshold in terms of the information you have to submit.”

He added: “That evidence has actually been submitted here.”

The Heath and Hampstead Society has called for a review of the council’s planning policy before widespread basement-builds threaten the foundations of Hampstead homes.

The conservation group claims more underground extensions will force subterranean waterflow through tighter spaces, with the pressure washing away foundations and damaging trees.

Mr Natsis’ application had previously been refused on the grounds that it went against council planning policy to have habitable rooms in an area prone to surface water flooding.

The living room and kitchen have been removed from the plans and replaced with a pilate’s room.

Mr Natsis’ representatives Tony Fretton Architects declined to comment.