The cache (a nano) is not located at the published co-ordinates, instead, it can be found at the following co-ordinates …
N 51 20 . (Blue) (Blue + Red) (Blue + Yellow)
W 000 46 . (Blue + Red) (Blue + Green) (Yellow)
Please don't leave any additional clues (subtle or otherwise) in your log.
And please could you bring something to write with.
And finally, please be careful of any thorns close to the cache.
You can check your answers for this puzzle on Geochecker.com.