The cache is NOT at the given co-ordinates, which is the car park. To find the cache you play a simple little game - I'm sure everyone knows how to play Snakes and Ladders. The cartridge you need can be downloaded from here:

I really don’t want to be rude, , but can I respectfully raise a few points before we start
Be sure you have the most recent cartridge. The most recent update was on 23 February 2023… it is rather frustrating to read logs telling of issues that were fixed months ago
I’ve watched people playing Wherigo in the past… READ WHAT THE SCREEN SAYS before pressing the “next” button, or you will struggle
The terrain can be muddy at times
Sorry, but this cartridge will NOT work on GPS devices...this is unavoidable in such a game as this. You will need a smartphone
Hope you enjoy it....
The landowner (Forestry Commission East England) does not assess the suitability or safety of the cache location. The cache placer and the cache finder have a responsibility to take reasonable precautions to protect their own safety and the safety of others. Hazards observed at or on route to the cache location should be reported to the cache owner. The Cache has been placed in accordance with the Forestry Commission East England agreement