A new survey reveals low levels of prosecution and crime reporting for those who use metal detectors illegally and dig up the countryside.

Commissioned by English Heritage and supported by its counterparts across the UK and Crown dependencies, the survey reveals that the threat to heritage posed by illegal metal detecting, or nighthawking, is high but arrest or prosecution remains at an all time low and penalties are woefully insufficient.

The Nighthawking Survey found out that more than a third of sites attacked by illegal metal detectorists between 1995 and 2008 are Scheduled Monuments and another 152 undesignated sites are also known to have been raided, but secrecy surrounding the crime means that it is significantly under-reported. Only 26 cases have resulted in formal legal action, with the punishment usually being a small fine from as little as £38. Illegally parking a car carries a £120 fine.

The crime is most prevalent in the central and eastern counties but rare in the west and south-west and almost unheard of in Northern Ireland and the Crown dependencies. Counties with the highest number of sites being affected by nighthawking are: Yorkshire, Norfolk, Suffolk, Essex, Kent, Lincolnshire and Oxfordshire. Honeypot sites such as Roman sites are often targeted repeatedly and the period after ploughing is the most common time, with considerable damage caused to crops and fields.

Illegal metal detecting is the search and removal of antiquities from the ground using metal detectors without the permission of the landowners or on prohibited land such as Scheduled Monuments. It is a form of theft and can be prosecuted under the Theft Act.

The heart of the problem lies in the vicious circle of under-reporting of the crime, which in turn creates a false picture of the seriousness of the situation, making this a low priority crime for the police. It is also compounded by the difficulty in collecting evidence.

Over time, the lack of successful prosecution has led to the lack of confidence of the victims in the legal process. The survey found out that only 14% of landowners, when afflicted by nighthawking, have reported it to the police. Most of them responded by tackling the culprits themselves or imposing a complete ban on metal detecting on their land.

The survey also calls for the setting up of a central database of reported nighthawking incidents and a tightening of the Treasure Act requiring all who come into contact with treasure finds, not just the finder, to report them. Full details of the survey including its recommendations are downloadable from the HELM Nighthawking website

English Heritage interim chairman Professor Sir Barry Cunliffe says: "Responsible metal detecting provides a valuable record of history, but illegal activities bring responsible ones into disrepute.

"Nighthawkers, by hoarding the finds or selling them on without recording or provenance, are thieves of valuable archaeological knowledge that belongs to us all. Even in the case when the finds are retrieved, the context of how and where exactly the finds were found has been lost, significantly diminishing their historical value. In the cases of internationally important material the loss of the unique evidence that these objects provide on our common history and origins is especially poignant. By establishing a clearer picture of the crime, this survey will help us to combat it more effectively."

A code of practice for responsible metal detecting is available from www.finds.org.uk/background/cop.php. The Treasure Act Code of Practice is downloable from the DCMS website at www.culture.gov.uk

Key recommendations of The Nighthawking Survey:

• Provide clear guidance to the police, Crown Prosecution Service and Magistrates on the impact of nighthawking on archaeological records and understanding, how to identify that it has taken place, how to collect evidence for prosecution and appropriate penalties
• Provide guidance to landowners on identifying nighthawking and what to do when they encounter
• Implement changes recently introduced in Europe which increase the obligation on sellers of antiquities to provide provenances and establish legal title; urge eBay to introduce more stringent monitoring of antiquities with a UK origin offered for sale on their website, as they have done in Germany, Switzerland and Austria
• Establish a central database of reported nighthawking incidents and promote its use
• Raise awareness of the positive effects of responsible metal detecting and the negative effects of nighthawking
• Reaffirm the contribution of the Portable Antiquities Scheme and support its continued operation
• Encourage the integration of metal detecting into archaeological work