Campaigners are seeking a judicial review to try and stop a council from turning nearly half a much-loved park into pay-to-use synthetic pitches.
The campaign began after Hammersmith & Fulham Council gave planning consent for 13 Astroturf pitches in Hammersmith Park, a basketball practice court and a new clubhouse.
The £2.2m scheme could be in place by spring 2014 after the local authority agreed to lease the land on a 35-year contract to Sport & Leisure Group, operating as PlayFootball.
It aims to replace a run-down pitch, vandalised changing rooms, disused bowling green and underused tennis courts. The public will have to pay to use all but two of the football pitches. The remainder of the pitches will be available to hire by the hour, with discounts for local groups and schools, said Hammersmith & Fulham Council deputy leader Greg Smith.
"Residents have been asking us to upgrade the all-weather pitch for several years," he added. "The facilities will be built at no cost to the taxpayer and breathe new life into the park."
However, local resident Virginia Ironside said: "The park is 2.49ha large and the area for development is 1.2ha - almost half. Leasing the land for 35 years is as good as selling it."
She added: "Money for the lease will go into a general pot and won't be dedicated to the park. Meanwhile, 24 mature trees and all the shrubbery will be removed.
"The existing pitches maybe rundown but they are still used by the community. I applied for a judicial review because I thought there was so little consultation."
Labour councillor Stephen Cowan agreed, accusing the Conservative council of deliberately keeping local residents in the dark about the deal.
Leasing rather than selling was a "ruse" to ensure that the council did not have to seek permission from the secretary of state, which is meant to happen when councils dispose of public parks.
PlayFootball declined to comment but the council told HW: "We can't say much until we know whether the review goes ahead. But the pitches are in disrepair and no one needs reminding how skint local government is."
It added: "There isn't lots of cash sloshing around to redevelop everything we would like to and this is a good way of getting money to boost the pitches."
Hammersmith Park has undergone refurbishment of its Japanese Garden in recent years along with the construction of new play facilities and a maze.
"Leasing land to sports companies for five-a-side football is becoming more common. If it brings people and revenue into the park it's good, but the money must benefit the open space not just the private enterprise. Some people argue that this is creeping privatisation but it's better than seeing parks deteriorate so badly that they are sold for housing."
Russell McDonnell, parks consultant