About 10 years ago we did the LAT fort walk to St Helen's fort at Bembridge IOW. I saw a nice bit of cord poking out of the shingle, pulled it and found a slightly battered diving torch on the end of it. Took it back to the boat and after 5 mins of trying to prise it open I managed to put new batteries in it expecting nothing and was amazed to find it worked well. It carried on working for 5 years, but sadly no more. Fabulous treasure.