At the edge of Pooh Corner, and with a view of the Prison, this cache is a quick park and grab.
As you can easily see, there are lots of places along this road where people stop to have a bite to eat, talk on their phone, or anything else that you might need to stop under the shade of a tree, and yet be off the bitumen. Therefore, the prison staff pay little attention to vehicles on the side of the road, so you will be fine stopping here for a quick park and grab, where you do't have to venture far away from the car at all.
You will need to bring your own pen