The cache isn't hidden at the given coordinates, you'll have to solve the following puzzle.
It can actually be found at N 50 4(A+H).C(E+F)(G*A) W 001 0(C-B).(E*G)(H-B)(A+H) where:
A = Arran
B = Canvey Island
C = Isle of Portland
D = Lewis and Harris
E = Rockall
F = Anglesey
G = Isle of Wight
H = Brownsea Island
At the time of publication, bringing a pair of thick gloves with you might prove handy. A checksum of all 15 digits will equal 61.
Logging Etiquette: Geocache hiders sometimes go through a great deal of planning to place their caches. As a result, they'd like to hear your feedback on whether you liked or disliked any aspect of the hide, the journey or location, or if you feel that some cache maintenance is required. Single word, acronym, or "copy and paste" logs may be easier when you have a lot of caches to log, but it doesn't tell the hider or other finders anything about your adventure (or lack thereof) in finding the cache. Please keep this in mind when entering your log.
Travelbug Etiquette: Cachers pay good money for TravelBugs and Geocoins. Please if you take a TB or GC from a cache will you ensure it is correctly logged in and out, also If you take one that still shows somewhere else please be patient before “grabbing” the item, it does not get its mileage by being grabbed and the last person to place may not have had time to log a previous find or the one you took it from. This is particularly important on busy and new caches. If you have an issue with a bug please e-mail the owner through their profile and advise them of the issue. They will be pleased to hear from you.
If you'd like to place a cache in this series, you are most welcome. There are just a couple of points to note:
1. Email den sure kalkun about your cache before you publish it. He will allocate a number to you.
2. Then let him know when it's published, and he'll add it to the bookmark list.
3. The island must be an actual island. Places with the name "Island" or "Isle" that aren't actually islands are not allowed. Any island is ok: sea, river, lake. It doesn't have to be a named island.
4. Only one "Island Treasures" cache per island. Sorry if your favourite island is already taken :)
5. You can place any type of cache in this series (Earth caches are particularly encouraged!) but the final container, if there is one, must be on the island.