Bafta-winning playwright Sir David Hare has called for an illegal extension which blots out light to his historic writing studio to be pulled down after a two-year planning row.

The “hideous” two-storey extension looms above the playwright’s Grade II-listed property in Hampstead which he has owned for more than 20 years.

The intellectual leftie has penned plays such as Olivier award-winning Skylight from its rooms, now darkened by the brick construction. The studio was also once owned by artist Mark Gertler, who painted his anti-war masterpiece The Merry-Go-Round there.

Sir David and his neighbours have called on Camden Council to bulldoze the “eyesore” in Old Brewery Mews after the owner applied to make alterations to the extension which he built without planning permission in 2010.

The celebrated 65-year-old playwright told the Ham&High: “Two years ago, in June 2010, without any warning an illegal extension was slung up in a few weeks at approximately two inches from where I work, and overlooking its glass roof.

“As the extension blocked out the light and endangered my roof, I complained to Camden Council at once. They agreed that the developer had no planning permission and that they would get it taken down.

“Two years later, I am still waiting for the council to act. They say they have a legal enforcement order from a court, but every time I ask them when they are doing to enforce their enforcement order, they say they don’t know.

“Apparently in this case enforcement doesn’t involve enforcing. Their latest excuse is that they now suddenly can’t find the legal owner of the property, in spite of the fact they have already taken a court order against him.

“I just don’t see how it can take two years to demolish a piece of illegal jerry-building. Truly, it bewilders me.”

Jenny Stevens, chairwoman of the local residents association, said: “It’s the most unbelievable eyesore. It does not fit in with the rest of the area, the materials are rubbish and it’s just ghastly.

“It’s taken the council a hell of a long time to do anything about it and the extension is supposed to have been taken down by now so it seems ridiculous for this new application to be made at all.”

Retrospective planning permission for the extension was refused in November 2010 and the owner was served an enforcement notice to pull it down.

A council spokesman said the officials would pursue the property owner through the courts after he ignored the council’s order.