With 86 per cent of parks departments reporting cuts to their revenue budgets, 19 per cent of councils are considering disposing of parks specifically, while 20 per cent have already devolved responsibility for some of their parks. The numbers are among figures published in the HLF's report State of UK Public Parks 2014.
The HLF surveyed parks managers, parks friends groups and the general public as well as undertaking a review of all existing data and benchmarking results against smaller surveys, such as those by APSE.
It found that 32 per cent of parks managers had seen cuts of 20 per cent or more to their revenue budgets, 15 per cent had to find savings of more than 30 per cent and two authorities recorded cuts of 50 per cent. Over the next three years 87 per cent of parks departments will have to find further savings.
The HLF found that the majority of parks managers and half of users thought their parks were in a good state but that "the immediate concern is that the condition of many of these parks is expected to decline significantly".
Chairman of the Parks Alliance, formed to stand up for parks, Mark Camley said: "This timely report provides the evidence to back up the experience of park staff and volunteers on the ground that the parks we know, love and use are close to crisis point.
"The Parks Alliance is keen to work with the Government now to halt the potentially disastrous decline in the green spaces, that are at the heart of British life and culture. Together with the people that create, maintain and use parks, national and local government has a duty to protect and improve the country's public green spaces for future generations."
Sarah Royal and Dave Morris of the National Federation of Parks and Green Spaces said in a statement that the report was "a shocking wake-up call which clearly necessitates immediate and effective national action."
The federation is calling for the Government to make parks a statutory service.
"The inspirational rise of the Friends Groups movement over the last 15 years has demonstrated the commitment of the public. We are now demanding an equivalent commitment from the Government to ensure adequate public resources for all green spaces, a statutory duty to manage these spaces to decent - Green Flag Awards - standards, and a national inquiry into these matters."
The chief executive of Keep Britain Tidy, which runs the Green Flag scheme, Phil Barton welcomed the report, saying that everyone had the right to live close to a good quality park.
"We know how important having skilled staff on site is to delivering this and ensuring our parks thrive and benefit the community. This is not something that can be achieved without the support of all those people who use, and care about, our parks.
"We encourage communities to engage with us and the National Federation of Parks and Green Spaces in our Love Parks programme and fight for every park to be well funded and managed to the Green Flag Award standard."
The HLF has issued five calls to action to halt parks' decline, which include asking people to support park campaigns run by Keep Britain Tidy and Groundwork as well as calling for all local authorities to appoint a parks' champion and for the Government to support delivery of good parks.
HLF head of landscape, Drew Bennellick, said some councils had found new ways, such as "hybrid arrangements" of paid and volunteer parks custodianship, of preserving the UK's rich parks heritage.
He added: "It's a huge concern as to what's going to happen in the future."
For Horticulture Week's full report see p20 and 21 of the magazine published on Friday.