When the metal detector tells you it's found something, you never know whether it's going to be the ringpull from a can of drink or a piece of history.

It's that buzz that motivates enthusiasts to search fields and beaches, listening to the strange melodic sounds that come from their machines.

When you hear members of Essex Detector Society preparing for one of their regular treasure hunts, it's like hearing an orchestra warm up as they adjust settings and test batteries.

Alan Radley, 55, a plumber from Kingsley Lane, Thundersley, has been detecting for about six years.

"I have always been interested in history," he said. "As a kid I used to go on camping holidays and clamber round castles and abbeys.

"But a lot of people get interested when Time Team comes on television."

Although Time Team presenter Tony Robinson is often scathing about metal detecting, enthusiasts in Essex feel it is unfair.

Their signal goes only a few inches into the ground so they do not disturb the deeper archaeology and they mainly check ploughed fields to see what is hidden in the churned up soil.

Last year, thousands of finds were reported by amateurs - obligatory since 1997 - and 506 items were declared treasure trove because of their age or significance.

Culture minister David Lammy even described metal detectorists as the "unsung heroes of the UK's heritage".

The Essex Detector Society has fostered links with the county's farmers and regularly organises charity rallies on farmland where enthusiasts pay to take part.

Former solicitor Peter Minshall, 76, of Falbro Crescent, Hadleigh, joined the society two years ago because he was looking for a hobby which would help him make male friends.

"I like being out in the fresh air and the excitement of finding something good - or anything really," he said.

Mr Minshall made one of the best discoveries in the club's history in October when he found a £1 coin-sized 7th century Saxon gold mount with a garnet in the centre on farmland.

All finds are reported to the finds liaison officer at Colchester Museum.

Items which are more than 300 years old or made from more than ten per cent gold or silver can be declared as treasure trove by the Essex Coroner and belong to the Crown, but if a museum wants to buy the piece, the finder and landowner share the money.

Mr Minshall seems to have the golden touch as he also found a gold mourning ring bearing the inscription J. Kinsman obyt 28 May 74 o.y.en.

The rings were given to mourners after a death.

Although walking around a field with headphones on is not particularly sociable, it is sharing knowledge, which makes the pastime more fun.

Every time someone bends down in the field and starts digging, the others look over and there is real excitement when something unusual is found.

While I was out in a field near Billericay on Sunday morning, Mike Andrews, 51, a self-employed decorator of Westwood Avenue, Brentwood, uncovered a 700-year-old silver Edward I shilling and immediately brought it over to Peter Hewitt for some advice.

Mr Hewitt, 53, of Brook Drive, Fobbing, has been detecting for 25 years and described the coin as a "once-in-a-lifetime find".

Mr Hewitt, a Chinese medicine practitioner at the Centre for Natural Health, in Wickford Broadway, said: "You get used to what you're looking for. But you never know what you'll find."

Mr Hewitt first became interested in the hobby when he dropped a silver ring while out walking in Norsey Woods, Billericay.

He saw someone with a metal detector and they helped him to find it within minutes."

Although machines can be adjusted to give different signals for different metals, Mr Hewitt added: "The skill really is our mantra slow and low'."

Walking slowing round a field is a hobby that needs patience and where the rewards are not guaranteed.

But you never know, there could be treasure hidden just a few inches beneath your feet.