A plan to build an extra floor above comedian Ricky Gervais’s office has sparked fears that one of Hampstead’s most cherished lanes could be transformed into a gloomy “tunnel”.

Ham & High: The current view towards the Savills building in Perrin's Court. Picture: Nigel SuttonThe current view towards the Savills building in Perrin's Court. Picture: Nigel Sutton (Image: � Nigel Sutton email pictures@nigelsuttonphotography.com)

Businesses, residents and councillors have united in their opposition to the proposal, which they claim will irretrievably harm pedestrian-only Perrin’s Court, which runs between Hampstead High Street and Heath Street.

Ham & High: Ricky Gervais at a gala screening of Ricky Gervais's new film The Invention of Lying, at Bafta in London. Picture: PA Images/Ian WestRicky Gervais at a gala screening of Ricky Gervais's new film The Invention of Lying, at Bafta in London. Picture: PA Images/Ian West (Image: PA Archive/Press Association Images)

Their greatest worry is that it will block out light that currently pours into the street, reducing its charm and potentially driving custom away from cafés that rely on outdoor seating, including Mani’s which is directly opposite the building.

A petition drawn up this week, which objects to the scale of the proposal and says it will create a “tunnel effect”, has already attracted dozens of signatures.

Emma Scott, co-owner of coffee shop Ginger and White, next door to the building, said: “We have been here for more than four years now and the feel of the lane and ambience is so perfect.

“We’re very worried about the light issue, and the fact you won’t have the sort of inviting look that makes people want to come here.

“It will kill the business if we don’t have that passing trade. It would be a real shame to over-develop this beautiful corner of Hampstead.”

The block was originally built to house the Ham&High in the 1960s, but is now leased by estate agent Savills.

Mr Gervais, who also lives in Hampstead, rents an office upstairs.

His publicist said: “Ricky has been asked to vacate the premises, but doesn’t have further information as far as the planning application.”

Last October, planning permission was granted to convert the first floor into two flats.

The developer is now seeking to add a second floor with a mansard roof to create two further flats.

The campaign against the application has been backed by the building’s original architect, Mayer Hillman.

Mr Hillman, 81, of Netherhall Gardens, said: “The street has a charm by virtue of the fact that it’s not like a cavern, because it’s got light and air.

“I don’t think an extra floor on top would add to its character. I strongly support the campaign.”

Cllr Linda Chung, of Hampstead Town ward, said: “The whole ambience will be ruined and the development will just take away people’s amenity, which is light and space.”

Cannan Ergul, 40, manager at Mani’s cafe, said: “We don’t want this, it’s going to be very hard for us. My regular customers have told me they would not sit outside with scaffolding and everything.”

Comments on the application can be made to Camden Council until October 22.

The developer declined to comment on the plans.