These are not the final co-ordinates.
Start by completing the 5 Lab Caches - History of Epping. An easy walk through Epping with simple answers to easy questions. On completion of the 5th Lab, the final co-ordinates to this Bonus Cache will be revealed - a short walk away.
Download the free Adventure Lab app. Now look on the map for Epping. Click on the History of Epping symbol and then enjoy the adventure.