Horrified neighbours are calling on Barnet Council to rip down an illegal extension which will see a family home converted into seven studio flats.

Residents in Temple Gardens, Golders Green, have watched as the four-bedroom house has gradually increased in size.

Since September, builders have constructed a ground floor extension, a loft extension and, more recently, a first floor extension.

The ground floor and loft extensions were approved by the council under the government’s “permitted development rights”.

But a retrospective application for the first floor extension at number 32 submitted by Ozcan Hassan last month was deemed “unlawful” by the council. It is now looking into enforcement action.

Historian Dr Helen Fry, 46, of Temple Gardens, said: “The neighbours couldn’t quite understand why a developer would come in and bolt a house on the back of a house.

“When we saw a first floor going up, we couldn’t believe it. We were just horrified that a property developer would come in and do this.

“He can’t be allowed to get away with it. It would send a message to other developers that they can ruin the neighbourhood.

“It’s crazy in a house of that size. We don’t want this to become a street of HMOs (houses in multiple occupation). It’s a quiet family street.”

Mr Hassan has also made controversial changes to two other Golders Green homes – 124 Hamilton Road and 90 The Drive.

The four-bedroom house at 124 Hamilton Road was converted into seven studio flats in 2012. A retrospective application last year was refused by the council which deemed the development unlawful.

The council served an enforcement notice and says the home has been returned to its original state.

Mr Hassan has also applied to convert 90 The Drive, a former doctor’s surgery, into a HMO with seven bedrooms. Barnet Council is currently considering this plan.

All three homes are owned by companies registered to an address in Farnborough, Hampshire, according to Land Registry records.

The Temple Gardens and The Drive houses were bought by off-shore companies in the Seychelles and the British Virgin Islands.

Mr Hassan, a Cypriot property developer, hopes to rent the Temple Gardens house to multiple tenants.

He is appealing to the Planning Inspectorate against the enforcement action.

He said: “I thought that a first floor development was a permitted planning development. I have appealed against the refusal because 14 Temple Gardens was permitted a ground floor extension and a first floor extension.”

Barnet’s planning boss Cllr Joanna Tambourides said: “Anyone carrying out building work to a property without the relevant planning permission is at considerable risk of an enforcement notice being served and ultimately the considerable expense of having to return the building to the way it was.”