The theft of a ?500,000 Barbara Hepworth sculpture from Dulwich Park shows how vulnerable public art works are to determined thieves

How do we stop thieves from making off with our public art works? The question arises from this week's disappearance of a Barbara Hepworth sculpture, Two Forms (Divided Circle), from its plinth in south London's Dulwich Park. The sculpture, which had resided safely in the park since 1970, is believed to have been stolen by scrap-metal thieves, who will only manage to realise a tiny fraction of its value (around ?500,000).

There are thousands of public works like Hepworth's in parks, gardens and town squares all round the country. Many curators are understandably reluctant to discuss the security measures they currently have in place. But Stephen Feeke, a curator at the New Art Centre, a gallery and sculpture park in Wiltshire, says flood-lighting is a good way to deter thieves and vandals. "You've also got to look at securely gating and fencing the perimeter of a park," he adds. "The important thing is to block access for vehicles: a bronze sculpture is far too heavy to carry off without a car."

Paul Ekblom, of the Design Against Crime Research Centre at London's Central Saint Martins, warns against the kneejerk imposition of fortifications. "We need to look at introducing security measures to new sculptures ? for instance, using forensic coding that might allow the metal to be traced. It's also important to make it clear that these thefts are totally unacceptable: our artists and culture ministers need to stand up and say: 'Shame on you.'"