Residents of a tiny street in Kentish Town have given hope to opponents of basement builds across London after winning what could be a landmark victory against their neighbour.

Households along Quadrant Grove successfully blocked plans to build a one-storey basement beneath one of the homes in their historic street last Thursday, after an animated town hall planning meeting saw councillors ignore the recommendations of their own officers.

Campaigners from other parts of London watching the decision hope it could spell an end to a growing trend of building downwards without planning permission, delivering a potentially serious dent to a lucrative industry for London’s property developers.

It has also been greeted with cheers from residents associations across Camden.

The fight has prompted some 25 residents associations across Camden to unite to form the Camden Residents Advice Committee (CRAC) in the hope of winning similar victories and blocking a trend seen in boroughs like Kensington and Chelsea where the number of basement builds has rocketed.

It comes after a long planning row between the group of 40 opposing residents and neighbour James Ireland.

Mr Ireland, an animator, had originally sought permission to build his basement by lodging a full planning application.

But the plan faltered after an independent report procured by Camden Council questioned the structural impact the construction would have on neighbouring houses.

He then applied to have the basement built under Permitted Development (PD) rights – powers allowing for “proportional” improvements to homes without requiring planning permission.

Outraged at the use of this “legal loophole”, the group of neighbours – which includes a high profile QC, a structural engineer and a prominent housing expert – threatened legal action against the council, who subsequently agreed to have the issue heard at the town hall.

The council had already permitted four basements to be built under permitted development rights this year.

Addressing councillors, Barbara Thorndick, of Quadrant Grove, said: “It is a strange world where someone can apply for a planning consent, fail one of the hurdles introduced by the council to protect neighbouring homes from damage, and then with advice from Camden’s planning officers, decide to use a different route to bypass the system.

“Quadrant Grove residents obtained an opinion on the matter from a leading chambers specialising in planning law. [Their] opinion was clear: this development involves engineering works, and as such cannot be a permitted development.

“As well as top lawyers we have also consulted one of the UK’s most respected civil engineers.

“Tim Chapman of Arup is a leading specialist in the field and was one of the authors of a Camden-commissioned report entitled ‘Guidance for subterranean development’.

“He was in no doubt that a basement construction of the type proposed is an engineering operation, and expressed surprise that anyone should think otherwise.”

Cllr Alison Kelly, speaking in support of the residents, said: “If it’s legally unclear [whether permitted development applies] then we should be backing the residents.

“We should not allow people to circumvent our policies by using the back door of the permitted development route when a planning application flounders.”

Council officers and the applicant were clear in their own view that permitted development powers do allow for basements like the one proposed.

QC Ian Trehearne told councillors on behalf of the applicant that engineering works were allowed under permitted development rights, adding: “The basement would lie entirely under the footprint of [the house].

‘‘If it has to be judicially reviewed, so be it.”

After debating for over an hour, the committee sided with the residents and chose not to allow excavation without full planning permission.

Ms Thorndick said after the victory: “We’ve had a load of other cases lining up behind our own battle, awaiting the outcome.

“They don’t know if they will get the same treatment as us, but I do think the decision will create ripples. It’s quite likely other councils will be looking at what’s happened in Camden.”