Restoration work on the Royal Navy's first submarine which was left on the seabed for 69 years has won a top conservation award.

Gosport's Royal Navy Submarine Museum won the �15,000 Pilgrim Trust Award for Conservation 2002 for its restoration of Holland One.

A team of conservationists spent 18 years and �1m on the 100-year-old submarine before it finally went on public display in November 2000.

The Holland One - built in 1901 - is the Royal Navy's oldest submarine and was salvaged in 1982 from waters off Plymouth where it sank almost 70 years before.

Naval prowess

Speaking at the London awards ceremony, chairman of the judging panel Loyd Grossman said: "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 a stunning display which brings the visitor a memorable experience."

To preserve the vessel, which was rotting away by 1993, the conservation team, led by Ian Clark, had to build a massive tank full of chemicals to draw out the corrosive materials.

Four years of soaking controlled the destruction and they set to work on displaying the submarine in a suitable environment.

Holland One was designed by the Irish-American John Phillip Holland and launched on 2 October, 1902.

Originally an experimental craft, conditions on board were so primitive that mice were used to warn submariners of dangerous exhaust gases.