Historic England (HE) has urged the council to scrap plans to demolish Victorian buildings and replace them with new homes and shops in Ealing Broadway .
Development managers Londonnewcastle, together with site owners Benson Elliot, propose to redevelop 9-42 The Broadway and transform it into 188 homes, 20 new shops, a new pedestrian route and a 5,000 square feet music venue.
An initial application was submitted in July 2015 but, following talks with the council and HE, was amended and re-submitted in January 2016 following heritage concerns.
But historic places advisor for HE David English, who was unimpressed by the amended application, said: "The Ealing town centre conservation area will no longer merit its status.
"This will directly result from the loss of buildings that make a positive contribution to the specific historic and architectural character of the area, and because of the scale and overbearing impact of recent developments."
Also opposing the development are the Victorian Society, Ealing Civic Society and Save Ealing's Centre who on Tuesday (February 16) launched a petition.
The re-examined application would demolish the Victorian building by Carphone Warehouse to increase the joining pavement, but would retain three out of four buildings developers claim the council has identified as making a positive contribution to Conservation Area.
Of the three being preserved, one is being kept in its entirety and the frontages of two others are being fully preserved.
HE claim the development will result in the loss of eleven buildings they describe as a "major part of Ealing’s Edwardian and Victorian built heritage."
But a spokesman on behalf of Benson Elliot and Londonnewcastle said: "We absolutely support the strong local desire to see the Conservation Area remain, of which our site is only a small part.
"It contains no listed buildings and we are preserving key facades that make a positive contribution to the CA, while replacing those identified as making a negative or neutral contribution.
"The new buildings have been thoughtfully designed using brick and stone that reflects the historic character of The Broadway, after extensive consultation with local communities since 2013 and with HE over the past year.
"We are of course disappointed with the Historic England response, but we believe our proposals will bring welcome vitality to this part of the town centre, balancing major investment while preserving its valued character."
Spokesperson Save Ealing's Centre, Julian Smith, said: "It would completely ruin the character of this part of central Ealing, much of which dates from its Victorian heyday when it was known as the Queen of Suburbs.
"If the scheme is approved it could lead to the loss of the entire conservation area, which would be a green light for developers to flatten the area and build high and dense characterless blocks which could be found in any town in the country."
An Ealing Council spokesperson said there are no plans to review the conservation area and this will not be affected by the planning hearing on February 24.