"Mysterious beastie" answer...

The answer to the Mysterious Beastie puzzle was... a swordfish! It was washed up at Berrow,  Somerset on 24th June 2013 and found by Andy. He says the sword was three feet long and the fish in total getting on for nine feet and would have weighed in the region of 1,000 lbs. The big puzzle is how it got so far into the Bristol Channel and if there are others out there! So far as I can tell, it would be on the edge or beyond its Northerly range in the Bristol Channel and may have died of hypothermia...