DIVERS who have dedicated the last three decades to scouring a stretch of the River Tees have had their thousands-strong hoard declared as treasure.

Rolfe Mitchinson and Bob Middlemass started searching the area at Piercebridge, near Darlington, in 1987 and hung up their scuba suits at the site in September last year.

Their finds over the years combined have made up an collection of more than 5,000 items dating from the late Iron Age to the post-medieval period.

The majority of objects, more than 3,000, are Roman in origin and include coins, brooches, military equipment, tools and figurines.

At an inquest yesterday in Crook, senior coroner Jeremy Chipperfield concluded the Roman artefacts and coins were treasure.

DELIGHT: Bob Middlemass and Rolfe Mitchinson speak outside Crook Coroner's Court

A delighted Mr Mitchinson, 78, of Bournmoor, near Chester-le-Street, said: “We’ve been diving in the River Tees for 30 years and today was an accumulation of all that hard work.”

Mr Mitchinson and Mr Middlemass, 70, of Belmont, turned their attention from deep-sea diving to river diving in 1987 at the request of Northern Archaeology Group founder member Raymond Selkirk.

The pair, equipped with their gear, headed down to the northern banks of the river on the Raby Estates-owned land.

“In 1987 a lot of the main finds came out and then the more river bed we uncovered the more finds we made,” said retired printer Mr Mitchinson. “It was like an Aladdin’s Cave.”

As well as diving in rivers on archaeological missions across the country, the duo have continued to return to the place where it all began.

In September last year they were asked to stop diving at the site to allow for a major study to be carried out by Reading University.

A report from the British Museum to the coroner stated their finds were a "votive deposit or series of deposits", meaning they were deposited for religious purposes without the intention of recovery.

The expert identified the hoard as appearing to be associated with the piles and cross beams of a Roman-period bridge.

Among the items two or more precious metal coins and numerous gold and silver objects containing at least ten per cent of precious metal.

The court heard Durham University Museums has expressed an interest in acquiring the hoard.

The divers hope their finds will go on to be displayed to the public.