The co-ordinates above are not for the cache, but Redhill town centre.
Technically, a cipher is a text in which each letter is substituted for another. Where entire words are substituted, it is a code.
Julius Caesar used the two ciphers which bare his name to pass messages securely during the Gallic wars. The first one merely substitued Greek letters for Roman ones, so anyone who found the message would think it written in Greek and would have to wait for a Greek speaker to arrive, before finding out that the text was gibberish. The trouble with this method however, was that your general had to be familiar with both alphabets to be able to decode the message and of course, the key to unlock the code is large.
To address this, the transposition cipher was invented in which each letter is substitued for one further up or down the alphabet, wrapping around at the ends. For instance, if you were to encode using 3 as a key: A would become D, B would become E and to decode, you'd just reverse the process. This is known as the Caesar Shift and the brainy among you should now know enough to be able to decode the ciphertext below. As for the rest of us, you could always google the 'key clue' in the hint.
You can check your answers for this puzzle on Geochecker.com.