To solve and find this Mystery cache you need to complete the "Warminster Wander" Adventure Lab.
The lab can be found at:
https://labs.geocaching.com/goto/warminster-wander
By completing each stage of the lab you will be given a letter and digit. Use these to solve the following and find the final location:
N51° 12.ABC W002° 10.DEF
Xvffvat tngr. Zntargvp.