After some initial trouble with my phone's onboard GPS (which 
doesn't like seeking without a reboot for some reason), we managed to get a lock, and half-walked half-ran across the park to a sparseish group of trees. The trunks of these trees were quite twisted and look like great hiding places for caches, and sure enough, my GPS got us down to '2 yards' next to a particularly gnarly one. We looked where the additional clue told us to, and it was there! Smashing hiding place, and unlikely to be muggled despite being in quite an open area!
We signed, dated and websited the log and replaced the cache exactly where we found it. It was quite dark by then, so the photo ended up being quite dark and the auto-focus wasn't at it's best - but it is at least readable. :-)
A nice cache-and-dash in a lovely area. Thanks for the hide 'searching sarab'!
