The cache is not at the posted coordinates.
To find this cache you will first need to complete the 5 Adventure Labs around Warmfield cum Heath parish. Once you have completed these you will get information in your journals to allow you make this Bonus find, plus a Hint will be given.
N 53 A.B W 001 C.D
These labs can be completed in any order, but please take note of the suggestion in the Adventure Lab's Description. It could save you a lot of walking!