UNEARTHING buried treasure is the stuff of story book fantasies but for many metal detectorists a night-time shadow has been cast over their hobby. Charlotte Shepherd went in search of gold with one of the Cotswolds best-known detectorists.

"THEY'RE thieves, nothing short of thieves," said Ian James, a Cirencester-based metal detectorist, whose 'finds' include an important Bronze-Age weapons' hoard now in the Corinium Museum.

The thieves to which he refers are nighthawks, the name given to metal detectorists who go out under the cover of darkness with the intention of selling what they find for personal profit, often on eBay.

Nighthawks flout the codes of practice that good metal detectorists obey by not seeking landowners' permission to carry out their detecting and refusing to declare what they find to their regional Portable Antiquities Trust.

For Ian, nighthawks spell big trouble. "I see evidence of Nighthawks all the time when I go out. I find their holes scattered around and I fill them in, otherwise the farmer will think it is me doing it," he said.

He believes the actions of the nighthawks, who do not bother to leave fields as they were found, are responsible for metal detectorists being portrayed in a bad light.

"We get tarred with the same brush as nighthawks," he said.

Edward Allsop, resident agent for the Bathurst Estate in Cirencester, said he will only allow metal detectorists on their land who have the support of the county archaeologists.

"If someone is reputable and is doing something which achieves county archaeological objectives, that would be fine with us," he said.

Gloucestershire Police recognise nighthawking as a problem and have flagged it up as something that they wish to tackle.

PC John Palfrey, rural beat and wildlife crime liaison officer for the south Cotswolds, says he is not concerned with the legitimate detectorists but with those taking objects for personal gain.

The police powers include theft and trespass laws. However, John admits that it is not a practical use of resources for the police to camp out in every field. Instead, they rely on a community approach.

"We want the community to be our eyes and ears," he said. "We want to know what is going on."

In an attempt to build up a bigger picture of the extent of the nighthawking problem, Oxford Archaeology are currently carrying out a survey, which runs until September 2008 and will attempt to turn anecdotal evidence about nighthawking into hard fact.

A spokesperson for Oxford Archaeology said: "We are not trying to do anything to deter responsible metal detectors and do not want to make life difficult for them. We appreciate the work that responsible metal detectors are doing".

Dr Alison Brooks is the collections' manager for the Corinium Museum in Cirencester and says the museum has a very good relationship with metal detectorists.

"My experience is very positive," she said. "I go to speak to detecting clubs and over the last few years we have received good objects from them."

Ian wants to show me how responsible detectorists behave, so I meet him in a field outside Cirencester one cold November morning.

He is keen that I do not reveal which field, because of trouble with nighthawks. "We do all the research on sites and enter into an agreement with a farmer and we go back and there will be holes everywhere because someone has been out in the night," he explained.

After 20 minutes, Ian starts to dig. "That's what we call bingo," he said, as he unearthed a Roman bow brooch.

Just 15 minutes later Ian hit the jackpot again, with a Roman coin clearly marked with the name and head of Roman emperor Commodus on it.

I feel like I have struck gold (or bonze) and am amazed when Ian tells me that the coin may fetch as little as £10. "A nighthawk would probably try to sell these things on eBay to the highest bidder."

It is not money that motivates Ian. "I've been doing this for 18 years and I am not a millionaire," he said.

His Bronze Age weapons' hoard in the Corinium museum has finally been assessed by the British Museum and valued by the Treasure Valuation Committee some three years after it was found.

The museum have agreed to pay Ian and the landowner £375 each for the entire hoard, which seems a small price to pay for such history. A nighthawk might feel he could get more by going via eBay or to a dealer.

Three years is also a long time to wait for an assessment and this may be one of the reasons the nighthawks choose to flout the laws.

Ian is interested in helping to build up an archaeological picture and for this reason he records all of his finds with Kurt Adams, the finds liaison officer at the Portable Antiquities Trust for Gloucestershire and Avon.

For Kurt, recording an artefact is the most important thing. "It can be of enormous value to the archaeological record," he said.

Metal detectorists who work within the laws were bringing in fantastic data, he added.

Nighthawks, however, have "stripped bare" some archaeological sites in Gloucestershire. "We have had sites that have been completely ransacked. Huge amounts of archaeological information has been lost," he added.

For Kurt, the way to tackle the problem is to take on the dealers. "The most positive thing is if we target the dealers," he said, "and ensure there is a more responsible market."

* To report suspected nighthawking call PC John Palfrey on 0845 090 1234.

* To record metal detecting finds go to www.finds.org.uk.

TREASURE ACT: A SUMMARY What is Treasure?

* Any object other than coins which was made of at least 10 percent of gold or silver and at least 300 years old when found.

* For coins, two or more, from the same find, made of at least 10 percent of gold or silver and at least 300 years old when found.

* Ten or more bronze coins from the same find at least 300 years old when found.

* Associated objects; any object, made of any material that is found in the same place or considered to be with another object that is treasure.

* Prehistoric metalwork, where there are two objects from the same find.

* Objects that would have been Treasure Trove - these objects have to be composed of a substantial amount of gold or silver and have been buried with the intention of recovery.

WHAT SHOULD I DO IF I FIND SOMETHING THAT MAY BE TREASURE?

You must report all finds of Treasure to a coroner for the district in which they are found either within 14 days of the day on which you made the discovery or within 14 days of the day on which you realised the find might be Treasure.

Failure to declare the Treasure carries a penalty of imprisonment for up to three months and/or a fine up to £5,000.