UNDER the cover of darkness and in lashing rain a daring group braved the ocean to retrieve a valuable prize.

Roger Radcliffe, chairman of St Agnes Museum, was in a race against time to beat the illegal trophy hunters he had heard were carrying off the bones of a 17m fin whale which had died on a Porthtowan beach in February.

After a couple of days the lower jaw bones, each measuring 5m and weighing 200kg, were jettisoned from the carcass and lay among the rocks.

In a bid to "rescue" these for posterity Mr Radcliffe rallied friends and neighbours for a night-time mission, taking 30 fathoms of rope and some timbers in a bid to transport the hefty treasures.

"The last whale stranded was after the Second World War so this time we felt there should be a record of it.

"We couldn't get a vehicle to the site so we had to carry the bones on our makeshift rigging."

The team had a licence from Natural England – required since 1994 as all whales are protected species – to make their conservation rescue and did so in two hours, getting both bones and a vertebra by wading through water above their wellies in driving rain and strong winds.

The bones were then hauled up on a boat trailer and delivered to a secluded and secret field.

Now the museum intends to follow the advice of experts from the Natural History Museum in London on how to preserve the bones for display.

Mr Radcliffe said: "The vertebrae has weathered quite well since February but the jaw bones are still glistening with whale fat and we have been told that the best way to accelerate the decomposition process is to bury the bones in elephant dung.

"As there isn't any of this in Cornwall horse manure is the next best option and we will be putting the bones below ground, hopefully this Saturday, to begin the procedure."

Decomposition may take several months but the museum is keen to add the bones to its natural history display, which includes its preserved leatherback turtle, and Mr Radcliffe hopes to create a theatrical display whereby people can literally "walk into the whale's mouth".

Ben Lockley, of Groundworks and Surfacing Contractors, is digging the burial site for free and the horse manure is being supplied by Sue Nile of HF Equestrian Services.