Last month the Court of Appeal ruled in favour of Merton Council, which plans to build space for 210 more children. The Protect Dundonald Rec group now wants legislation to stop councils "appropriating" public land.
General secretary of the Open Spaces Society Kate Ashbrook called the ruling "deeply depressing". But parks consultant Sid Sullivan said: "They may have lost the battle but they haven't lost the wider strategic issue." Merton is considering new models for green spaces.