A petition to save the Curzon cinema in Mayfair - which is under threat of closure - has been signed by almost 18,000 people.
The historic cinema has been on Curzon street since 1934, but it may be shut down after property developers made a noise complaint.
Developers 38 Curzon Ltd want the cinema to pay for soundproofing to make it easier to sell the £2m flats being converted on the floors above. However, the cinema will not be able to afford the £500,000 bill for the work and wouldn't be able to get planning consent because the auditorium's walls are listed.
The petition calls on the mayor of London, Sadiq Khan, and the Westminster council to step in.
It reads: "It is an absolute travesty that developers 38 Curzon Ltd have called on the Curzon to fork out £500,000 to soundproof luxury properties they are building above it.
"They know that the cinema doesn’t have the funds. They know that the venue is listed and would face an uphill struggle to get permission to change its interiors. This is a de facto attempt to close the Curzon through the backdoor."
The Curzon Mayfair is not the only iconic London cinema struggling to survive. One of the few Art Deco cinemas remaining in London - the Towers Cinema on Hornchurch High Street - is going to be knocked down and replaced by a Lidl.
Lidl said the new shop would retain some of the building's historic charm. A spokesperson for the retailer said:
We are aware and understanding of concerns raised by a number of local residents, and as a result plan to retain the 'Towers' lettering and create a public art installation at street level, integrating a piece of the site's past history within the new scheme and creating a focal interest on the frontage of the new store.