Some simple projections using your GPSr, a feature many of us are unaware of.
You can always use your trusty compass and guesswork to distance (or reverse coordinates / distance), but using the projection feature will produce a much more accurate result.
The projections given, are very accurate, for those that prefer to use mathematics to solve this type of thing. If using your GPSr you will have to do some rounding. The distances are not far so you will still end up pretty close.
Start at the above coordinates, also the best place to park, and project a waypoint 172m at 316.2 degrees true. This will bring you to a wide section in a small bridge; a good check that you did your projections correctly.
Now from here project a second waypoint 180m at 266.5 degrees true, this is the cache site.
There is no need to venture onto private proporty.
Cache is a pill bottle.
Please exercise extreme stealth, and ensure the cache is well hidden before departing. The original hide was located by muggles and the stash note used to start a fire in the original hiding place!