Refused plans for an “excessive” three-storey basement the size of two double decker buses could still become a reality despite opposition from neighbouring Hampstead residents.

Hampstead resident Stefanie Drews has lodged an appeal against Camden Council’s decision to block plans for the demolition and reconstruction of 59 Maresfield Gardens in Frognal - which would include a three storey basement and underground swimming pool.

Residents are concerned that if the decision is overturned, the excavation work will cause damage to neighbouring properties.

Netherhall Neighbourhood Association committee member Stephen Williams said: “We feel disappointed.

“With their next door neighbours, they could have looked at ways of doing the development which would be less intrusive and less aggressive to the adjacent properties, a tall building to go up a storey or two, in order to achieve what they want.”

The retired architect, of Maresfield Gardens, added: “It is excessive in this situation and in planning terms we are opposed to it.”

The original planning application was to demolish the existing 1950s home and rebuild it as a sunken house with three underground levels, as well as additional depth to make space for a swimming pool.

It was refused by councillors at a planning committee in June following strong objections from the community.

A spokesman from LOM architecture and design said: “The applicant, Hampstead resident Stefanie Drews, is looking forward to residing permanently at no 59 with her children.

“She has engaged actively with neighbours and is keen to enhance the area with an environmentally-friendly family home.

“The proposal is identical to a planning permission granted in 2008 and was recommended for approval by planning officers, who were supportive of the high quality design.

“A Basement Impact Assessment was submitted and independently reviewed by engineers acting for the council.

“This confirmed that the structural stability of neighbouring properties would be protected, and that there was no basis for concerns around ground water.”

A date has not yet been set for the appeal hearing.