The coordinates take you to the remains of the 14th Century chapel of St Mary's. An earlier incarnation of the church now close to Etal manor (and well worth a look inside)
The cache is located a short distance away. To find it you need to work out the following from the fence overlooking the chapel:
The total number of vertical fence posts: AB
The total number of horizontal planks (look closely!!): CD
The cache can be found at:
N 55 BD.AC5, W 2 6.D7A
Check sum of BDACDA is 24