Zoe Chan, 40, removed the original ground floor of her Hampstead property, part of a former mid-18th century stable block that was listed as being exceptional architectural and historic interest.
She then installed reinforced concrete walls and flooring, permanently obscuring historic brickwork.
The work, which included lining the cellar with concrete and installing modern services, removed historic features and causing irreversible harm to the historic fabric of the building.
Chan was convicted of carrying out extensive unauthorised alterations to the cellar of the Grade II* listed property in Frognal without listed building consent.
At Highbury Corner Magistrates’ Court on November 12, District Judge Baker ordered Chan to pay a total of £71,841.71 within six months, including a £48,000 fine, £21,841.71 in costs, and a £2,000 surcharge.
In a sentencing note, District Judge Baker said: “I am satisfied so that I am sure that Ms Chan, a professional woman with experience in property development and experience in working with professionals both instructed by her and within Local Authorities, was reckless in failing to ask the relevant question – ‘do I need permission?'”
Councillor Adam Harrison, cabinet member for planning and a sustainable Camden, said: “This case sends a clear message: We will not tolerate unlawful works that damage our borough’s heritage.
“Listed buildings are protected for a reason—they are part of our shared history. Anyone considering alterations must seek proper consent. We will take robust enforcement action against those who disregard these rules and remain committed to preserving the borough’s historic environment, taking enforcement action where necessary.”
An appeal to the Planning Inspectorate was unsuccessful, with the Planning Inspector finding that less intrusive measures were available.
Grade II* listed status is given to buildings of “more than special interest” and accounts for just 5.8 per cent of all listed buildings.
