It's all in the find

SIMON Holmes holds the delicate object up to the light. "It's a medieval mirror case, dating from about 1270 to 1350," he explains.

He unclasps the hinge, still working perfectly seven centuries after being made. Inside the two mirrors, probably made from small pieces of polished metal, have long gone. But the casing survives, showing they would have been a stylish hexagonal shape.

It is a little smaller than a modern woman's make-up compact but probably performed the same function. So, I ask, a medieval maiden would have used it to check her lippy?

"Yes. At least until Robin Hood came up behind her... Or perhaps it belonged to Maid Marion!" jokes Simon.

That is the power of an item like this. Hold it and you have a tangible link to our ancestors. You cannot help but speculate about the mirror's owner, her lifestyle, her story. Yet we would never have recovered this remarkable relic if it had not been for a history enthusiast from Rotherham with a metal detector. The previous week he was one of a rally of like-minded folk scanning a field near Ripon.

When the bleeper went off he recovered the mirror case, which otherwise might have been destroyed by the farmer's plough. Then he did two very responsible things. Firstly he did not try to clean up his discovery - that could easily have damaged it.

Secondly, he brought it to the York Archaeological Resource Centre (ARC), St Saviourgate, York for Simon to examine, who quickly declared it "the best find I have seen all year".

Archaeologist Simon is a finds liaison officer based at the Yorkshire Museum. But every Thursday he goes to the York ARC with finds liaison assistant Dave Evans and the man known as the "godfather" of metal detectorists, Jim Halliday, from Norton. And they wait.

Usually they do not have to wait long. A steady flow of people pop by to show what historical artefact they have unearthed armed only with a metal detector and an enthusiasm for the past.

These are the unsung heroes of historical research. Professional archaeologists can only excavate small, specific sites, usually before they are built on. So great swathes of open land would otherwise go untouched, and this is the hunting ground of the detectorists.

More than 200 of them have descended on the Hutton Wadesley Estate near York this weekend. Enthusiasts from as far away as Germany and Dublin are there to scan fields close to Long Marston, looking for relics from the Battle of Marston Moor fought there in 1644.

"You get all sorts. Lawyers, bankers, doctors, builders... all walks of life," says the event organiser, Anne Laverty, from Yeovil, Somerset. "They are like-minded, they enjoy the outdoor life, and love finding something for the first time in hundreds of years."

Her event also raises money for the Royal Agricultural Benevolent Institution - "putting something back" for the landowners who volunteer their land to the detectorists.

Back at York ARC, Jim Halliday is showing me his metal detector. These days they are very sophisticated. It can "learn" any object passed beneath it. Then you can programme it to ignore that object or look for more of the same.

"You can set it to detect pound coins," said Jim. He doesn't bother looking for smaller change now. "You used to be able to get a pint for ten pence when they first came out..."

Most detectorists are not in it for the money, but for the magic of discovering a piece of history. That is certainly true of Jim, who has been metal detecting for about 25 years.

"I was a building inspector and would go and see the foundations. There were some wonderful things in the foundations that nobody was bothered with at all."

This fascination for the past beneath his feet, originally inspired by some archaeological training he undertook in 1947 when he was 14, led Jim to start metal detecting.

"It's archaeology for the masses," he says. "The parson and the gentry used to do it. When the metal detector came out, it was archaeology for everybody."

Metal detectors can discover items dating right back to the copper age, 2500BC. And because they are staring at the ground intently detectorists often spot non-metallic artefacts such as pottery too.

Les Sweeney has been metal detecting for 20 years. He concentrates on areas around Copmanthorpe and Bishopthorpe, and one of his proudest finds was a hammered silver farthing dating from the reign of Edward I (1239-1307).

Searching a 30-acre field for a tiny coin seems a solitary business, I suggest.

"It is as solitary as you wish it to be. You can join a club and go out with 25 people at the weekend, enjoy their company, show each other your finds.

"I don't go out with a club any more because I am interested in one area. I'm an independent detector."

Frank Hudson, from near Barnsley, another regular visitor to the ARC, says this is a good time for detecting, after the harvests have been lifted. And he points out how detectorists are regularly called on to help people find everything from lost wedding rings to a JCB digger bolt fallen into a grain silo.

For ten years detectorists like these have been bringing their historic finds to York ARC and Jim has helped to catalogue them. That adds up to one of the best archives of finds in the country.

The database is a boon to historians. Horse harness pendants, copper signet rings, pilgrims ampulas: it is all here. The best finds, such as an Anglo-Saxon jewelled brooch discovered in Riccall a year ago, end up on display in the Yorkshire Museum.

Undoubtedly the Middleham Jewel was the most famous and valuable find in years. This diamond-shaped gold pendant, which could have been worn by Richard III, was discovered by an antiques dealer with a metal detector near Middleham Castle in 1985.

After a long wrangle which nearly saw the jewel leave the country in the hands of a private collector, the Yorkshire Museum successfully raised £2.5 million to buy it for display.

The Treasure Act 1996 governs what people should do with finds. Most searchers conscientiously report them, but there are those armed with metal detectors, known as the "nighthawks", ready to pounce on a place where artefacts have been found to plunder treasure for themselves. That is why precise locations of finds are kept secret.

The nighthawks have given metal detectorists a bad name, said Jim, whose own finds grace both Malton and Yorkshire Museums' collections.

"We don't like to be seen as gold diggers because we know 90 per cent of what we find is rubbish," he said.

Unearthed a piece of history? Take it for examination to the York ARC, St Saviourgate, on any Thursday from 10am to 3pm.

BBC TV programme Hidden Treasure is also holding a roadshow at the Yorkshire Museum on Saturday October 11 where finds will be examined by the experts.

Updated: 09:35 Saturday, September 13, 2003