Thanks for the encouragement! I agree grid references are a pain, one digit wrong and it's completely wrong!
A few months ago the puzzle came to the attention of The Armchair Treasure Hunt Club in the UK. I recently joined their forum but all interest had already dried up. I'm amazed how so few people get into this hunt.
I believe there will be a new clue for Christmas, let's hope it's enlightening! Good luck with your solutions.