More than half of the 100 schools surveyed said that playtime bullying had dropped since they spruced up their grounds.

The research was carried out by the Learning Through Landscapes charity which awards schools grants to re-develop their playgrounds.

It found that almost a third of the schools believed vandalism had reduced since the makeovers, while 84 per cent felt that interaction between pupils had improved.

One of the schools surveyed was Lee Manor primary in Lewisham, south London, which has transformed its grounds over six years using grants of more than pound;12,000.

Once a barren expanse of asphalt surrounded by a graffiti-covered wooden fence, the playground now contains trees, a wildlife area with a pond and woodland trail, colourful murals, and a “fairy glen” featuring a bridge over a model troll.

Head Barbara Smith said: “It’s not that you plant a tree and bullying stops automatically,” she said. “It is more to do with the process. Pupils, parents and the community worked together on the grounds, and it has raised expectations.”

The “Grounds for Celebration” report is at www.ltl.org.uk