In reply to andyinglis:
As in, the one with Forest Mechanics on it? I've not been to Brin in years so my memory could be terrible but isn't it quite close to the entrance gate into the woods? Kind of to the left of the 1st boulder you see (with Hit Me on it) and slightly downhill, maybe tucked behind some other boulders so not immediately obvious. But I could be talking rubbish...
Brin seems incredibly popular these days so I'm sure someone who knows will be along to help soon.