Campaigners who lost a three-year battle to prevent a primary school's expansion into public playing fields are now calling for a change in laws to safeguard public open spaces.

Protect Dundonald Rec campaigners ran out of legal weapons in the offensive against Merton Council's plans to expand Dundonald Primary School.

Their appeal was rejected by The Court of Appeal earlier this month.

Now Wimbledon residents concerned about the future of the playing fields are launching a new campaign to reform laws which give councils the power to "appropriate" public space.

A Protect Dundonald Rec spokesman said: "This judgement is not only sad for Dundonald, it is a disaster for public open space in towns and cities throughout the country.

"It has effectively over-written the national protection for public open spaces. From now on any council can remove public rights over any land simply by using the 'Merton template'."

Despite objections to the 579sq m expansion of the site, judges ruled the council's decision to approve the school expansion was rational, given the wider community interest in providing more school places.

Lawyer Anthony Fairclough, a legal information manager at Matrix Chambers who lives in Wimbledon and supports the Dundonald campaigners, said there were two legal changes which could strengthen the role of communities in challenging developments in public open spaces.

The first would be to change the rule that the only person who can appeal against the granting of planning permission is the person who applied for it.

That rule has forced individual residents to challenge councils with expensive judicial reviewing proceedings.

The second would be changing the way local authorities can "appropriate" public open space.

Mr Fairclough said: "The law at the moment basically gives councils a wide discretion to determine whether the land is needed for its current purpose or not."

Protect Dundonald Rec campaigners are now calling on the council to put the remainder of Dundonald Rec into a trust before building work begins, to safeguard it from future development.

Councillor Stephen Alambritis, leader of Merton Council, said: "We are proud to be one of the greenest boroughs in London and are committed to ensuring Merton’s parks and recreation grounds can be enjoyed by residents today and for generations to come.

"And as part of this, we are already looking at a number of possible models, including trusts, for green spaces across the borough."