Work to build a large two-storey extension at the Highgate house where rock band Pink Floyd formed in the 1960s has provoked anger from neighbours.

The Victorian house in Stanhope Gardens was sold at auction last September along with the property next door. It is understood Sham Masterman, a Singaporean developer, paid £1.2million for each house.

A planning application to build an extension at the rear of the properties has been submitted to Haringey Council and is pending a decision.

But preliminary work to restore and enlarge the properties has already begun, upsetting nearby residents who say the extension will be “completely out of keeping” with the rest of the street, which falls within a conservation area.

The owner is seeking consent to demolish part of the properties and build a two-storey extension with small dormer roofs. The revised proposals have attracted 30 letters of objection from nearby residents.

They claim the development is out of keeping with the area and will block light to neighbouring properties.

Philip Hill said his garden and fence are in serious danger of collapse because the ground level has been reduced.

“The developer has been in there and done a huge amount of work on a massive extension even though they don’t have planning permission,” he said. “Everyone is up in arms. The extension is completely out of character.”

Cllr Lyn Weber, who represents Crouch End on Haringey Council, said a temporary stop notice was issued by the council when iron girders were erected, but this has expired.

“It’s really unfortunate that when big changes are occurring to any property that residents aren’t involved early enough,” she said. “A lot of the issues could have been discussed before. This far down the line it becomes more emotional.”

A spokesmwoman for Haringey Council said: “The council’s planning enforcement team issued a temporary stop notice to the owner of this property and all extension work has now stopped. Following concerns raised by local residents, an amended planning application is now in progress and the consultation process has been extended for any further comments to be taken into consideration before a final decision is made.”