Proving that conservation is not just for fine art or historic buildings, a Winchester man has scooped a major award for saving a submarine.

Freelance conservator, Ian Clark, of Itchen Abbas, together with the Royal Navy Submarine Museum, Gosport, has won the UK's premier conservation prize for restoring the Navy's first submarine, Holland 1, which was launched in 1901 and lay on the seabed for 69 years.

At the award ceremony in the British Library, London, Loyd Grossman, chairman of the judges and broadcaster said: "Among an outstanding 2002 short list, this amazing submarine project stands out.

"It has everything: a fascinating story, pivotal to British naval prowess; a bold conservation procedure, based on sound scientific principles and carried out on an unprecedented scale; and stunning display which brings the visitor a memorable experience. Everybody should go and see it!

"We warmly congratulate conservator, Ian Clark and the Royal Navy Submarine Museum on their tremendous achievement."

Led by Mr Clark (41), the team beat off competition from a shortlist that included entries from the National Trust, the Wallace Collection and the Museum of Science and Industry in Manchester.

Mr Clark, who is splitting the £15,000 prize money with the museum, said: "This award represents a fantastic boost and real vote of confidence in conservation of our industrial and maritime heritage."

And he paid tribute to Hampshire County Council for helping fund the restoration project and providing technical support.

Holland 1 was the first of five submarines secretly commissioned by the Royal Navy at the beginning of the 20th century. "The Admiralty resisted submarines at first," said Mr Clark.

Admiral A.K. Wilson, Controller of the Navy, famously described them as "underhand, unfair and damned un-English".

Built by Vickers, Sons and Maxim at the Barrow-in-Furness shipyard, Holland 1 cost £35,000 and displaced 120 tonnes. Her maximum speed was five knots under water and she could dive to 100ft.

Her crew comprised two officers, six ratings and three white mice. "The principle was the same as canaries in coal mines," explained Mr Clark.

"If the mice died, it was time to surface because of the build-up of carbon monoxide fumes from the petrol engines."

After 12 years service as an experimental vessel, much of it under The Solent, Holland 1 was decommissioned and sold for scrap.

But a dramatic twist of fate saved her for future generations. A storm broke out while she was being towed to a South Wales scrapyard, severing her towrope. Unmanned and unstable, she quickly sank to the bottom of the sea a few miles off the coast near Plymouth.

There she stayed for the next seven decades until she was salvaged by Royal Navy divers in 1982, when her conservation began.

The vessel was cleaned, treated with anti-corrosion chemicals and put on display at the Gosport museum. But by 1993, she was suffering from severe rust and repainting proved futile.

A new solution was needed. So in 1994, the museum built a giant glassfibre tank to enclose the submarine and filled it with 800,000 litres of sodium carbonate.

Soaking the submarine in this way removed the chloride ions - more commonly known as salt - that was causing the corrosion.

In December 1998, the soaking tank was drained down and final tests carried out. Chloride levels were now found to be extremely low - the treatment had worked.

A specially humidity-controlled gallery was also built to display the submarine. When visitors enter the gallery, they breathe moisture into the dry atmosphere, which if it were allowed to build up, could stimulate more rust.

The gallery has been equipped with a powerful dehumidification system that keeps the humidity below 40% relative humidity, preventing start-up of the corrosion cycle.

The Pilgrims Trust Conservation Awards are to reward excellence in preserving our heritage and is open to conservators for completed projects on individual artefacts, museum collections, historic buildings, library and archival treasures.