Can you keep ship-wrecked goods?

Beach-combers have been told to stay away, but scavengers are out on Branscombe beach in Devon, where booty is washing up from the stranded ship MSC Napoli. So can they keep what they find?
Brand new BMW motorbikes have been wheeled out of the shingle by keen treasure-hunters. Wine casks, perfume and car parts littering the shore have been rolled clear or tucked under the arm.