One of my favourite "after school" viewing pleasures when I was a kid was The Partridge Family, a half-hour musical sitcom detailing the humorous adventures of a family trying to make it as a rock group. This cache was placed in honour of Shirley Partridge, who is the matriarch of the family, and is played by Shirley Jones.
One of my favorite episodes: Prior to their first concert on the road, Shirley plans several alternate routes by backtracking from the end point, and everyone imagines what they will see on each route.
You can park at the posted coordinates. In order to find this cache, walk along the sidewalk to get to the reference point, and find a telephone pole with a metal tag with 6 vertical letters. You will be plotting a waypoint as follows: take the first two letters, determine the sum of their numeric values and that will be your bearing (true north). Take the 3rd and 4th letters, add their numeric values and that will be your distance in meters.
I am hopeful that people will find this one a little easier to spot than the last one I hid in the vicinity!
Since this is a letterbox, please leave the stamp behind, and be careful when peeling back the flap where the log sheet is stored.