Close by you will see an open concrete pipe, this runs under the road in front of you and into the hedge row the other side.
This was put in place when the bypass was built to allow Badgers and other animals to cross safely. You can also see the wire fencing that runs around this park has an extra fence that has been dug in to prevent animals digging under and trying to cross the road.
If you have time, walk up the steep bant to the picnic table. From here you can see over to the White Horse at Westbury.
You are looking for a small tube hidden inside something natural, you may need tweezers.
You will not need to climb over any fence.